General
- Glossary of Power
Conversion Terminology
- Inside
a Power-Cube Transformer - what's inside those small transformers you have all around
in your house plugged to the power outlets and powering small electronic equipments with
low voltage
- Power Supply
Failures - power supply failures can be frustrating, expensive, and time-consuming
events because many power supplies are highly complex circuits, with many components
operating near the edge of their envelope, and when they fail, they tend to destroy most
of the failure evidence with them
- PSPICE power
electronics - Information Pspice,tutorials,library components,download,cursos,power
electronics papers,ups,ballast electronics,PWM,power factor correction,switching power
supply,datasheets,links.
General power supply design
- Avoiding
the Seven Sins of Power Supply Design - power supply designers can commit seven
specific sins that cost time and money
- Ceramic
capacitors in dc/dc-input filters: OK, but watch out for those transients - Designers
now have new reasons to use ceramic, rather than tantalum, capacitors. But be careful.
- Choosing a
heat sink: some tips and recommendations
- DC Power
Supplies - This is an introductory slide set on DC power supplies.
- Design
guidelines help dc/dc converters work properly over long lines - some background and
design tips help ensure optimum converter operation under various long line conditions
- Designing Power
Supplies the Easy Way - Very High Voltage ICs, or VHVICs, make designing a power
supply easy
- Fault
Tolerant Power Supply System Uses the Droop Method of Current Sharing
- Feedback
isolation augments power-supply safety and performance - properly designed isolated
feedback is crucial to maintaining safety on many power supply designs
- Just-In-Time Power
Supply Design - just-in-time power supply design is increasingly untenable because
simple power supply is not so simple anymore
- Linear
Supplies feel the (lack of) heat from switchers in low-wattage applications - ICs that
implement advanced supply techniques are challenging linear supplies by lowering costs,
cutting size, and increasing efficiency
- Linear
Supplies feel the (lack of) heat from switchers in low-wattage applications - ICs that
implement advanced supply techniques are challenging linear supplies by lowering costs,
cutting size, and increasing efficiency.
- Linear vs
Switching Supplies: Weighing All the Options - the choice between linear and switching
board-level power supplies is sometimes clear-cut but can be sometimes hard to do
- Power Conversion
in Line-Powered Equipment - application note in pdf format
- Power.national.com -
collection of power supply design information from National Semiconductor
- Powering the
big microprocessors - modern microprocessor power-supply design must furnish many amps
at a tightly controlled voltage level and respond quickly to heavy load transients
- Power-supply
reliability: a practical improvement guide - path to high reliability is a
well-managed process that starts in the product's definition phase and continues long
after the first shipment
- Proper
layout and component selection control power-supply EMI - All power-supply components,
including voltage regulators, inductors, and transformers, and their layout determine the
amount of EMI a supply generates. An overview covers the mechanisms and physical
principles governing the generation and propagation of power-supply electrical noise.
- Truth or Consequences
of LDO Regulators - low-dropout regulator, better known as LDO, is a special type of
regulator where the minimum required voltage between the input-output voltage (the dropout
voltage) is significantly smaller than predecessor parts
- Using
thermistors in temperature-tracking power supplies - Simple linearizing schemes make
it easy to use thermistors to implement voltage-regulator designs with
temperature-dependent outputs.
Power distribution in circuit board
- DC-DC
Converters Deliver Better Performance For Distributed Power - with their enhanced
efficiency and features, modular components deliver high currents and low voltages, in
small packages
- Decoupling
capacitors: use them or fail
- Distributed
power takes center stage - distributed power has become a strategic architecture for
digital systems
- Generating
3.3V from 5V - low drop out regulators are the answer
- Good design
enables hot insertion of power supplies - hot insertion of power supplies offers many
advantages, but it can cause lots of problems unless you prepare for it in your design
- High-Density
Power Components Add Flexibility To Distributed-Power Design - correct load
partitioning, thermal management, and filtering help to achieve successful
distributed-power solutions
- High-end
digital systems give a thumbs down to rules of thumb - lower voltages, higher current
transients, and higher clock rates render rules of thumb uselsss for designing
power-distribution-system decoupling networks
- Hot-swapping
power - Hot-swap power controllers can make the difference between a product that
lasts long enough to be a classic and one that's just a bus crash waiting to happen.
- Hot-swap
your way to high availability - follow live-insertion board-design guidelines to keep
the sparks from flying
- Packaged
DC-DC Converters Solve Distributed Power Dilemmas when used properly, off-the-shelf,
isolated dc-dc converters save space, reduce component count, and simplify design
- Simple
Techniques Minimize Cross-Coupling in Distributed Power Systems
- Use local
bypass capacitors to meet rigorous high-speed-system demands - when conductors look
like inductors and supply lines must absorb amps of fast-edge glitchiness, low-inductance,
locally applied bypass capacitors come to the rescue
Mains power connection
Mains power filtering
Regulatory compliance
Component selection
Measuring power supplies
Wiring power supplies to load
Car power
Portable equipment power
-
Adjustable high voltage supplies
Low power
Safety notice: Even though very many low power high voltage circuit
produce vely low currents which are not as such usually dangerous, they can still produce
dangerous shocks.
- 25-kV
generator tests insulation - a car ignition coil can function in place of a
high-voltage transformer to make high voltage source
- Air Ionizer
- 230V AC are changed in DC and they are multiplied in + 6500V roughly
- Auto Air Purifier HV
Generator - operates from 12V
- Cockcroft-Walton
Diode Voltage Multipliers - this document describing some basic voltage multiplietr
circuit topologies, pdf file
- Electronic Air Cleaner
HV Generator - operates from mains voltage
- High Voltage
Generator - capable of generating up to 50KV, frequency of operation is around 1.2KHz
- High Voltage
Generator for Low Current Applications - pdf file
- High Voltage
Generator for Flash and Geiger Tubes - very low battery current, pdf file
- High
voltage supply: 12VDC in, 12KV out
- How Van de Graaff
Generators Work - Most of us have seen the device, known as a Van de Graaff generator,
that makes your hair stand on end. The device looks like a big aluminum ball mounted on a
pedestal. Have you ever wondered what this device is, how it works, why it was invented,
or how you might build one yourself?
- Low
power 12000 volt power supply - draws power from the 120vac power line but it uses a
small 6KV camera flash trigger coil, output signal is isolated from the power line,
circuit can only deliver about 5uA of current, pdf file
- Negative/Positive
Ion Generator - Ion generator powered by 110-240V mains supply. It uses the standard
Cockroft-Walton multiplier circuit - a ladder of diodes and capacitors to pump the output
voltage up to the level required.
- Super
cheap 1500V power supply (small LASER supply)
- Tiny tiny inverter
design - little efficent circuit that runs off of 3V, and charges up a little 1 uf
250V cap all the way up in about 30 seconds
High power
High voltage spark circuits
-
- 500,000 Volt Tesla
Coil - 18" sparks
- Cheap and Quick
Tesla Coil - uses neon transformer and spark gap
- Homepage of K.Ukkonen -
lost of Tesla Coil links
- Jochen's High Voltage
Page
- Make myself a Tesla Coil
- Matt Behrend's
Tesla Coil Web Site - This site is devoted entirely to the high voltage technology
discovered by Nikola Tesla over 100 years ago. This site was created for the purpose of
providing useful information to anyone who is interested in actually building a Tesla
coil, or just curious about the technology.
- Nikola Tesla Page,
tesla coils
- Solid State
Tesla Coil/High Voltage Generator
- Tesla
Coil Calculations - coils and capcitors
- Tesla Coil Mailing List Page -
The tesla coil mailing list covers the topics of tesla coil construction, operation,
measurement, and use. Topics range from sources of materials, opinions of commercial tesla
coil kits, measurement of electical fields, photography of coils, construction techniques,
etc.
- Tesla
Coil Page
- Tesla
coil pictures
- Tesla Coil Safety
Information - This document is provided to assist the amateur in understanding the
significant dangers associated with tesla coils.
- The Electrum Project -
some technical information about a very large tesla coil project
- TUBE-type
Oscillator-Driven Tesla Coil
High voltage experimenting
Stun gun circuits
Special application power supplies
Linear power supplies use dissipative regulator components to
achieve regulation. This dissipative regulation means conversion of excessive power to
heat. When using a linear regulator you have usually an unregulated power supply which
gives somewhat higher voltage than your electronics needs. You put a dissipative regulator
between the power source and your electronics circuit. This regulator keeps the voltage on
the output stable (as long as the input voltage is high enough). The regulator itself
converts the the power determined by voltage difference (unregulated voltage - output
voltage) times output current to need.
Linear power supplies are generally easy to construct (there are
very easy to use ICs for this or they can be built quite easily using discrete components)
and can easily give good quality output voltage (stable output voltage and low noise). The
disadvantage of them is low effiencely (lots of heat dissipated in power supply). The
linear regulator used in regulated linear power supplies, utilises simple techniques of
controlled energy dissipation to achieve a regulated output voltage independent of line
and load variation. It is, therefore, inherently inefficient, especially when a wide input
voltage range has to be catered for. When building a linear regualated power supply which
takes mains voltage and outputs low voltage, the following parts are needed; a buly low
frequency mains transformer, large heat-sinking is required to dissipate the heat
generated by the regulating element and very large filter capacitors are required to store
enough energy at the voltage to maintain the output for a reasonable length of time when
the mains source is removed (during mains AC voltage zero crossing).
Theory
An unregulated power supply is by far the simplest linear power
supply type. It consists of a mains transformer, rectifier and a output voltage filtering
capacitor. The ac from the transformer secondary is rectified by a rectifier of some type.
Typically a block rectifier or four individual diodes such as 1N4004 types are used as
rectifier. In some applications a centre tapped transformer and two diodes are used for
rectification. The principal advantage of a bridge rectifier is you do not need a centre
tap on the secondary of the transformer.
After the rectifier the power supplies generally have some form of
filtering capacitor which converts the voltage from rectifier (varies between 0V and full
rectifier voltage generally at twice of mains frequency) to a smooth DC voltage.
An unregulated power supply generally gives somewhat higher output
voltage when it is not loaded at all (genrally around 1.4 times nominal voltage). The
output voltage starts to drop as the load increases, and they give the nominal output
voltage at the nominal load current. If the load increses from this, the output voltage
drips below nominal voltage until maximum output current is reached (after that some
protective elements like overheating protector or fuse stops the excessive current from
flowing).
In general, most devices that are battery powered can handle a
voltage of at least 10% higher. And they usually work also with somewhat lower voltages.
This is because most transistors and Analog ICs are designed to work within a range of
voltages. This is why an unregulated power supplies can be used with many such circuits.
What is a "wall wart"? I'm sure you have a number of these
things around; I sure do. These are those little (or not so little) black (but sometimes
white) cubes with AC power connector blades on one face. You plug it into the wall and it
converts the AC voltage to DC voltage at some specified current. Once you plug it into the
AC outlet, it sits there like a black (or white) wart on your wall, thus the term of
endearment, "wall wart." Typical wallwart includes an unregulated power supply
as described above.
- 12 Volt 30 Amp Power
Supply - This circuit uses a single 7812 IC voltage regulator and multiple outboard
pass transistors (TIP2955). This power supply can deliver output load currents of up to 30
amps.
- 12V RMS to
10V Voltage Regulator - will take a 12V RMS sinusoidal input from a transformer and
provide a 10V DC output at 100 mA with very good regulation
- 12 Volt to 9
Volt DC Converter
- 48 Volt Phantom
Power Supply - This is a simple 48 V regulated linear power supply design that will
provide up to 60 mA of current. This circuit is based on the Texas Instruments TL783C high
voltage adjustable linear regulator IC. This circuit is short circuit protected.
- 78xx regulator
board - circuit board and ccircuit for making voltage regulators based on 78xx ICs, in
pdf format, text in Finnish
- A constant 5 volts DC
power supply - This is an example of a power supply to power anything requiring 5
volts DC. This circuit takes low voltage AC in (9-16V AC).
- Active
preloading provides sinking capability - a simple add-on circuit enables a unipolar
power supply, usually a current-sourcing circuit only, to sink current from a load
- Build a simple 13.8V
Power Supply Unit- A power supply with output voltage of 13.8V and a current capacity
of 5A.
- Car 12V
converter - simple circuit to connect car 12V to 9V, 7.5V or 6V
- Circuit
reduces VCC ripple in audio band - regulator circuit which reduces noise and ripple by
at least 35 dB over the audio range of 100 Hz to 20 kHz and provides a clean source of 5V
power for driving audio circuits in portable applications such as cellular phones and
multimedia notebook computers
- DC power
supply - simple circuit based on 78xx fixed voltage regulator IC, those ICs are
available for some fixed voltages between 5 and 24V
- Discrete LDO
Regulator - The discrete LDO design presented here came about because of the need for
an LDO (low drop-out regulator) for 5V designs. There are better performing LDO parts, but
they tend to be either single sourced or expensive. This one can be made from common
components. The performance parameters are very crude : 5V nominal at up to 10mA from
6-16V.
- Explanamtion and
experiment about regulated DC power supply - many power supply designs for different
voltages, built from discrete components
- High Current
Power Supply - takes very few parts and outputs up to 10A, regulation not very good
- Increasing
Regulator Current - you can boost 78xx regulator output with one power transistor
- Linear
supply uses switch-mode regulation - You can use simple circuits to implement small,
regulated plug-in power supplies. This basic and versatile 5V supply uses a zener diode
and an emitter-follower transistor.
- Logic PSU with Over
Voltage Protection - 5 volt regulated power supply for TTL and 74LS series integrated
circuits, includes output overvoltage fault protection
- Low-drop
regulator - outputs 5V at 1A, constructed from discrete components, in postscript file
format
- MOSFET
circuit ups regulator's output current - use a current mirror and a power MOSFET to
increase the output-current capability of an IC-voltage regulator
- Power Supply for
Preamplifiers - gives +/-15V outputs and takes power from external AC power supply
- Power supply with +5V,
+15V and -15V outputs
- Regulated
12 Supply - provides a regulated 12 volts at 0.5 amp to a load, built from discrete
components
- Regulated 12 Volts
DC Power Supply for Vacuum Tube Heaters - this 7812 based circuit circuit can be used
with low-hum audio applications such as microphone preamps and for other applications that
require well regulated 12 volts
- Regulated
Power Supplies - many designs, for 6V to 400V, both tube and transistor based designs
- Regulator
excels in noise and line rejection - certain electronic circuits require extremely
low-noise power supplies and this circuit provides very good quality power output
- Regulator
generates sub-bandgap voltages - 100-mA regulator that uses a dual linear-regulator IC
to produce output voltages below 1.25V from 2.9 to 5.5V input-voltage range
- Sam's Schematic
Collection of various circuits - includes many regulated power supply circuits
- Simple
5V power supply for digital circuits
- The
Spyder - an Eight-Output Pedalboard Power Supply - outputs regulated 9V DC
- Ultra Low Drop
Linear Regulator - MOSFET based linear voltage regulator with a voltage drop of as low
as 60 mV at 1 ampere, output 12V up to 3A, includes short-circuit crow-bar protection to
guard the components against over-stress during accidental short at the output
- Universal DC-DC
Convertor - This circuit will generate a smaller DC output voltage from a larger DC
input voltage.It is quick and simple to make and by changing the value of the zener diode,
the circuit can be universally adapted to provide other output voltages. The circuit and
all diagrams represent a DC convertor with 12V battery input and 9Volt DC output.
- Voltage
Regulator - simple regulated 12V power supply using one transistor regulator circuit
- 0
- 300V Adjustable Power suppy - This is a simple circuit which can provide an
adjustable voltage source of 0 to 330 Volt. The supply is short-ciruit proof: the current
is limited to about 100mA.
- 1.2-25VDC
at 4A power supply schematic - built using discrete transistors and 741 opamp, read circuit description
- 1A Variabe
Power Supply - This circuit takes in 240V AC and outputs a regulated DC at voltage
sange of 2-15V DC up to 1.5A.
- Adjustable power
supply using LM317 - voltage regulator for 1.2V to 35V output voltages and up to 1A
load
- Adjustable
Power Supply - well filtered variable 1.2-30 volts at 5 amps using LM338K
- Build
a Variable Voltage Supply for Cheap - This is a variable voltage 1.5A supply that can
be built cheaply and used for bench experimeting. With a 24VDC wall wart, this board can
produce anywhere from 23V to 1.2V
- Dual Power
Supply - adjustable two output laboratory power supply with meters, circuit designed
by Joel T. Retanan, 222k pdf file
- High Current
Regulated Supply - uses pair of 3N3055 transistors to give out currents up to 15A
- L200
Regulator Circuit - easy to build a power supply with one single L200 IC, offers a
variable current limit of up to 2 A, as well as voltage regulation
- Variable 3 -
24 Volt / 3 Amp Power Supply - regulated power supply can be adjusted from 3 to 25
volts and is current limited
- Self-switching
Power Supply - output variable from 3.7V to 8.7V and supply switches itself off when
no load is connected across its output terminals
- Simple regulator
circuits for regulating DC power - regulators built from zener diodes and transistors
- Säädettävä
jännitelähde 0-24V 4A - 0-24V 4A adjustable power supply, text in Finnish
- Säädettävät
regulaattorit - adjustable regulators using L200CV, LM317T and LM338K regulators ICs,
text in Finnish, but pictures are prettu much self explanatory and text not needed, output
voltages in rage 1.2V..36V and current 1A..5A
- Variable Power Supply
- based on versatile L200 voltage regulator, independent voltage (3-15V) and current
(10mA-2A) limits
- Velleman
K1823 Power Supply - This small power supply provides a regulated voltage between 1.5V
and 35 volts at 1A that can be used in many applications. This is a full documentation of
a kit sold by Velleman.
Negative voltage generating circuits
CD player adaptors
Misc
A switching power supply is a device transforming the voltage from
one level to another. Typically it is taken from the mains and transformed to the DC
levels that logic requires in a PC or a battery loader. The main differences between the
linear and switched-mode regulator are in the size, weight and efficiency.
Since a switched-mode converter can operate at significantly high
frequencies, then a smaller transformer using ferrite cores can be used. Also since the
high rectified mains voltage is chopped, then energy storage for hold-up can be
accomplished on the primary side of the step-down transformer and so much smaller
capacitors than the linear counterpart can be used. A switching-mode power supply (SMPS)
is a power supply that provides the power supply function through low loss components such
as capacitors, inductors, and transformers -- and the use of switches that are in one of
two states, on or off. The advantage is that the switch dissipates very little power in
either of these two states and power conversion can be accomplished with minimal power
loss, which equates to high efficiency. Usually a switching-mode power supply is circuit
that operates in a closed loop system to regulate the power supply output. Although the
benefits of switched-mode techniques are great, there is a penalty paid in the increased
noise present at both input and output of the supply due to the power switching
techniques. Also the associated control circuitry is much more complicated than its linear
counterpart.
The switching mode power supply contains a transformer/coil and to
make this as small as possible, the internal switching frequency has to be quite high,
something typically in the range between 20KHz and 1MHz. This also makes the device
noiseless to human ears. The oscillator noise is often conducted onto the input and output
lines with a frequency that varies with the load.
There are many different types of withing power supplies. Off Line
Switching Mode Power supply is a power supply in which the ac line voltage is rectified
and filtered without using a line frequency isolation transformer. After rectifications
and filtering the voltage is converted to the needed voltage using a swithing regulator
circuit, which usually provides also isolation function (power goes though high frequency
transformer). The typical PC power supplies (AT and ATX power supplies for example) are
built in this way.
For DC/DC type conversion there are many alternatives. One option is
to use switched capacitor converter (usullay used for voltage doubling or negative voltage
generation). Switched capacitor type converters are generally used only for low power
applications. More often used technique for low and high power is switched inductor
converter. This converter type can be used for converting voltage up, voltage regulation
and for current regulation.
Designers often categorize power converters into two basic types:
isolated and nonisolated. These categories refer to the relationship between the input
power ground and the output power ground. Many applications require isolation between the
two grounds. The isolation requirement often stems from various safety agencies, and the
main purpose of isolation is to protect personnel from exposure to dangerous voltage
levels. In some cases, the grounds must have sufficient isolation so that applying a
potential of 1500V or more between them shows no indication of breakdown. An isolated
power-converter design imposes several extra design challenges on a power-supply designer.
Switchers are suitable for many applications, but not to all. Unless
you're willing to spend a great deal of blood, sweat, and tears on the job, it's a bad
idea to try to use a switching power supply to power a sensitive analog circuit.
Switch-mode power supplies tend to generate impressive amounts of noise - conducted
through the power supply rails, radiated, induced, etc. - and this noise can quite easily
cross-couple onto your analog signal lines. For some analogue applications switchers are
suitable, but then you need to use a very "quiet" switcher type.
- 1V,
100A supplies: Plugging efficiency leaks - ICs that consume 1V, 100A are just around
the corner. Manufacturers of regulator ICs and power semiconductors are busy designing
circuits and devices that fulfill that lofty requirement.
- All About
Switching Power Supplies - two practical design examples, pdf file
- A New
Continuous-Time Model for Current-Mode Control - conference paper in pdf format
- A
simple guide to selecting power MOSFETs - As power-supply size and performance demands
increase, selecting the right switching devices becomes more complex. A straightforward
method simplifies the selection process, speeds your development, and helps you to
optimize your design.
- Ceramic
capacitors in dc/dc-input filters: OK, but watch out for those transients - Designers
now have new reasons to use ceramic, rather than tantalum, capacitors. But be careful.
- Circuit
trade-offs minimize noise in battery-input power supplies
- Comparator
improves regulator's efficiency - UC384X family of current-mode PWM regulators
requires a current shunt or some other component to develop a voltage proportional to the
output current, in this example an extra amplifier reduces necessary voltage drop need so
reduces losses
- Consider
IGBTs over power MOSFETs at frequencies to 100 kHz - evaluating the performance of
IGBTs and high-voltage power MOSFETs for switching applications requires a common set of
applications and assumptions
- Crossing
the boundary: strategies for feedback across an isolation barrier - Designers often
categorize power converters into two basic types: isolated and nonisolated. These
categories refer to the relationship between the input power ground and the output power
ground. Many applications require isolation between the two grounds. Various isolated
design approaches have their options, difficulties, and trade-offs.
- Current
Doubler Topology: Myth and Reality
- Design Tips
- information on transformer measuring and design and also general power supply design
- Effective
MOS Transistors Drive Circuits For Bridge Converters
- Feedback
isolation augments power-supply safety and performance - properly designed isolated
feedback is crucial to maintaining safety on many power supply designs
- Finding the
keys to flyback power supplies produces efficient design - quick tutorial on
flyback-power-supply design may help clear out some of the cobwebs
- Friendly
software eases power-supply design - free software from power-products vendors saves
you time and effort when you are configuring and characterizing swoiched mode power-supply
designs
- History
of Switched Mode Power Supplies - The document describes various switched mode power
supply techniques pre 1987. This document is a good introduction to various switched mode
power supply techniques.
- IC and
capacitor improve isolated supply - many isolated power supplies typically use an
optocoupler and a reference to provide feedback to a controller to maintain a constant
output voltage, this uses different method to provide controlled output voltage
- Isolated
Feedback Techniques for Power Supplies
- Isolated
power conversion: making the case for secondary-side control - Two designs with the
PWM control on the secondary side highlight the benefits of secondary-side control and
point the way toward more optimum architectures for future converter designs.
- Leakage Inductance:
Living With Leakage Elements in Flyback Converters - review of the magnetic and
electric models of the two-winding and three-winding transformers
- LIER circuit
helps power-supply efficiency - leakage-inductance, energy-recovery (LIER) circuit
ecovers energy stored in the primary leakage inductance and delivers the recovered energy
to one of the power supply's outputs
- Little
ICs generate big voltages - ICs and small modules simplify the task of generating the
high voltages for displays and their associated backlights
- Low-voltage
power sources keep pace with plummeting logic and µP voltages
- Method
provides self-timing for synchronous rectifiers - Synchronous rectifiers are MOSFETs,
driven in such a way as to perform a rectifying function. They often take the place of
diodes in the output-rectification stage of switching power converters, because of their
lower on-state power loss. In power circuits, synchronous rectifiers are often complicated
to use because of timing issues. This document gives some solutions to solve this problem.
- Modify
your switching-supply architecture for improved transient response - by taking a
different approach to switching-supply design, you can develop an architecture that
improves overall supply performance in critical transient specifications
- Power
Converter Survives High-Energy, Low-Frequency Surges - high-energy, low-frequency
surge transients can damage electronic circuits, unless the circuit configuration is
equiped to handle this type of transient
- Powering
New-Generation Microprocessors - there is pressure to abandon inefficient linear
regulators on PC motherboards with switching power supplies
- Saturable
bead improves reverse recovery - this circuit uses a saturable inductor bead to
control the switching diode's reverse-recovery time and, therefore, to reduce EMI in
swtiching power supply
- Simplified
calculation of magnetic and electrical losses in unity power factor boost regulators
- Smart
Solid-State Fuse Helps Designers Cure Boost-Converter Ailments - The challenge is to
get desired load disconnect while retaining use of the humble catch diode and unadorned
boost topology
- SMPS switch mode power
supplies design - oftware tools and design examples
- Spice
predicts differential conducted EMI from switching power supplies - not only can
predict the exact EMI levels produced by a switched-mode power supply, but also can
produce plots that allow you to easily evaluate your design and the effectiveness of the
EMI filter
- Spreadsheet
simplifies switch-mode power-supply flyback-transformer design - designing flyback
transformers for switch-mode power supplies involves many calculations, this spreadsheet
helps it
- Synchronous
rectification aids low-voltage power supplies - synchronous rectifiers can improve
switching-power-supply efficiency, particularly in low-voltage, low-power applications
- Switching
converter uses planar magnetics - planar-magnetics technology is growing in popularity
as a design option for dc-dc converters
- Switching-Mode Power Supply Design
- A good power electronics circuit design hypertext with problem silving tips
- Switching-regulator
design lowers noise to 100 µV - extending unconscionable amounts of bypass
capacitors, ferrite beads, shields, Mumetal, and aspirin to ameliorate noise-induced
effects is no longer the only way to tackle switching-regulator noise, there are nowadays
low-noise ICs available
- Switching
regulators demystified - Key to good design of switching-regulator circuits is a solid
understanding of the fundamental theory of operation.
- Switching-regulator
supply provides low-noise biasing for varactor diodes - Low-voltage systems often need
a locally generated high voltage. Even for an application as noise-sensitive as
varactor-diode biasing, a carefully planned switching-regulator-based design and layout
can provide the necessary bias voltage.
- Tandem
hookups enhance utility of dc/dc units - flexibility you can gain by connecting
isolated, compact dc/dc converters in parallel or series allows low-cost, standard parts
to meet system needs with minimal cost and space penalties
- Transistors
tame perfidious leakage inductance - In flyback converters that use primary
regulation, the loose coupling between the power secondary and the primary auxiliary
windings often results in poor cross-regulation. This situation arises mainly from the
leakage inductance but also comes from the level of the primary clamp voltage. This short
article showss the circuitry you can adopt to avoid the leakage-inductance problems.
- Troubleshooting
and Repair of small Switchmode Power Supplies
- Two
diodes change demagnetization-signal polarity - some ideas for flyback design
- V2
Architecture Provides Ultra-Fast Transient Response in Switch Mode Power Supplies
- 2 Watt
Switching Power Supply - from 6V to 14V
- +30V
power supply with +5V - This is a power supply which makes about +30V with +5V power
supply. The high DC voltage (up to +50V) is made with the alternating voltage using the
voltage amplification rectification circuit.
- 6V to 12V
Converter - This circuit can provide up to 800mA of 12V power from a 6V supply. The
circuit is simple, about 75% efficient and quite useful.
- 9-100v
P.S.U. - This is the circuit for powering battery valve radio sets. It gives out 100V
DC.
- Battery
booster delivers 75W - uses isolated DC/DC converter in a nonisolated configuration to
boost a 48V battery voltage to 60V
- Boost
converter controls 12V fan from 5V supply - temperature-controlled PWM boost converter
allows operation of a 12V brushless dc fan from a 5V supply
- Boost
converter generates three analog rails
- Coilless
step-up converter yields dual outputs - provides regulated 5 and 3V supplies from a
wide input range without the need for inductors
- Converter
has high efficiency at low loads - micropower components and circuit design of this
converter enable it to maintain 90% efficiency for load currents below 8 mA, circuit
outputs 5V DC
- DC to DC
Converter - will produce a 85V voltage from +3V, usable for low power applications
- DC to DC
Converter - low power converter which converts 3V to 85V, uses standard 12 VAC center
tapped power transformer and single bi-polar NPN transistor
- Hex inverter
makes low-cost switching regulator - simple and low-cost circuit converts 5V to 12V
- High power 12
V to 300 V invertor for high repeat rate medium power strobes
- High-voltage
circuits for electrostatic microphones - circuits that can generate the required
high-voltage for electrostatic microphones used in bat detectors, circuit can be used to
generate a voltage of about 70V using a current of about 4 mA at 6V input voltage
- Li-ion
boost circuit uses no inductors - circuit to mainstain regulated 3.3V supply for
portable applications
- Low-cost
switcher converts 5 to 24V - low-cost, three-transistor low power boost switching
regulator
- One 9V battery
gives +18, +25, +33V - how to make voltage booster using MAX1044 charge pump converter
IC
- Panel
meter power supply - isolated 9.1V 2-5 mA output from 8-30V input, in pdf format, text
in Finnish
- Single
cell lights any LED - This circuit allows you to light any type of LED from a single
cell whose voltage ranges from 1 to 1.5V. This range accommodates alkaline, carbon-zinc,
NiCd, or NiMH single cells. The circuit's principal application is in LED-based
flashlights, such as a red LED in an astronomer's flashlight, which doesn't interfere with
night vision. White LEDs make handy general-purpose flashlights. You can use the circuit
in Figure 1 with LEDs ranging from infrared (1.2V) to blue or white (3.5V).
- Step-up/step-down
converter takes 2 to 16V inputs - switcher where input can range above and below the
regulated voltage, circuit accommodates a wide range of input and output voltages and
supplies output currents as high as 500 mA
- 3.3-V
Supply Taps Power From The 12 V PCI Bus
- 5-to-1.8V
Converter Works Without Magnetics
- Add
trimmable current limit to dc/dc supply - you can add a simple, two-transistor circuit
to a standard, step-down dc/dc converter to provide an adjustable limit for the output
current
- Bipolar
transistor boosts switcher's current by 12 times - This circuit uses a minimal number
of external parts to raise the maximum output current of a 0.5A buck switching-regulator
IC to more than 6A.
- Boost
controller drives buck converter - by adding an external switching transistor, you can
use a step-up dc/dc converter to step down voltages to produce an efficient
battery-powered power supply, this example circuit can step down inputs as low as 2V to
outputs as low as 1.25V, with efficiency as high as 80%
- Buck
converter works efficiently from phone line - A switching converter provides an
inexpensive way to generate 5V, 18 mA (48V, 5 mA maximum) directly from a standard phone
line.
- Buck
regulator generates flexible VTT for PECL - circuit to generate output which can both
source and sink current
- Circuit
provides 1.5V, 7A bus termination
- Inductorless
converter provides high efficiency - produces a regulated 2V output with as much as
100 mA of load-current capability from 2.4 to 6V input voltage
- SEPIC
generates 5V at 100 mA - Some applications require an input voltage higher than the
breakdown voltage of the IC supply pin. In boost converters and SEPICs (single-ended
primary-inductance converters), you can separate the VIN pin of the IC from the input
inductor and use a simple zener regulator to generate the supply voltage for the IC. This
design shows a SEPIC that takes a 4 to 28V input and generates 5V at 100 mA.
- Single
resistor improves V2 converter - V2 control offers a significant improvement in
transient response by using two voltage feedbacs, example circuit is for generatign
voltages in 1.8-3.3V range
- Step-up/step-down
converter takes 2 to 16V inputs - switcher where input can range above and below the
regulated voltage, circuit accommodates a wide range of input and output voltages and
supplies output currents as high as 500 mA
- Supply
derives 5 and 3.3V from USB port - This circuit derives its power from a USB port and
produces 5 and 3.3V supply rails for portable devices, such as digital cameras, MP3
players, and PDAs. The circuit allows the port to maintain communications while, for
example, charging a lithium-ion battery. IC2 boosts the battery voltage, VBATT, to 5V, and
IC3 buck-regulates that 5V output down to 3.3V.
- Switched-capacitor
regulator provides gain - switched capacitor idea to convers 12V to 3.3V or 5V
- The
MIC4680 Switching Regulator - simple circuit which outputs +5V
- Three-input
supply powers 3.3V portables - single-ended primary-inductance converter accepts input
voltages ranging from 3 to more than 6V and produces a regulated 3.3V, 200-mA output
- Wall-cube
dc/dc converter is 85% efficient - ubiquitous 12V wall cube generates an unregulated
dc voltage of 8 to 18V, depending on line voltage and load, this circuit generates a
regulated 5V 400 mA from it very efficiently
DC-DC converters with isolation
Mains powered switchers
- 13.8 V / 15 A from
a PC Power Supply - Depending on the PC model, power supplies are rated anywhere
between 150 and 240 W. They are mainly primary switching power supplies with power
switches arranged in a half-bridge configuration. This article describes how to modby a PC
power supply to give 13.8 V output at high current. Most power supply units are designed
according to the same principle (half-bridge configuration) and hence the following
described modification should be applicable also to power supplies from other producers.
- CoolSET
TDA16831..-34 for OFF-Line Switch Mode Power Supplies
- Electronic
transformer dims halogen lamp - switched-mode power supply for a halogen lamp,
commonly known as an electronic transformer, is a clever and simple device which can be
enhanced with dimming control
- Miniature
off-line supply delivers low power DC - simple circuit which takes 120V AC and outputs
regulated 5V 30mA which is isolated from the mains line
- Open-loop
power supply delivers as much as 1W - For VCRs, TVs, and other equipment that requires
a standby mode, you must supply power to a µP when other components are asleep. Any
active power-supply circuit also needs to be more cost- effective than the standard
structure using a metallic transformer. This circuit is simple switcheer that takes 230V
AC and outputs 10V 90mA
- Step-down
rectifier makes a simple dc power supply - a simple and useful nonisolated rectifier
features voltage step-down operation, acceptable Class A line-current harmonics, inherent
short-circuit protection, and, optionally, a regulated output
Other switching circuits
- 5V
Supply Derives Power From 3-Wire RS-232 Port - The circuit of Figure 1 produces a
semi-regulated 5V output from an RS-232 port. Unlike a PC-mouse supply or comparable
circuits that rely on the modem-control signals DTR and RTS, this one operates with a
3-wire port (GND, Rx, and Tx), and obtains power only from the Tx line. The output
current-about 8mA-is sufficient for CMOS microcontrollers and other low-power circuits.
- Switch
intelligently controls current - this circuit can intelligently control ac or dc
current when connected in series with a load
Transformerless power supplies are very useful in some applications,
but remeber that eliminating the transformer eliminates the safety factor. You should this
type of power supply only if the circuit you want to power has no external connections to
anything else (unless they are properly isolated from the rest of the circuit). Line
isolation is essential for safety with respect to electrical shock - no part accessible to
the user must be connected to either side of the power line. A regular transformer
provides this automatically.
- Off-line
power supply requires few parts - This simple non-isolated off-line power supply can
provide up to 150 mA 5V and uses only a handful of components from 110-230V AC input
voltage. Note that the low voltage output is directly connected to the mains; it can not
be used when the low voltage part can be touched.
- Transformerless
mains power supply - This power supply does not really excel in power efficiency, but
it is the cheapest and most compact solution for a small power supply. Note that the low
voltage output is directly connected to the mains; it can not be used when the low voltage
part can be touched. With the component values of the schematic, the circuit can supply
12V /15mA max.
- Transformerless
supply fits CATV applications - coaxial CATV systems derive their power from a 60-Hz
square wave that shares the center conductor with the television channelsm this circuit
generates 10 mA at 5V DC from it
The power supply converts the alternating current (AC) line from
your home to the direct current (DC) needed by the personal computer. In a personal
computer (PC), the power supply is the metal box usually found in a corner of the case.
The power supply is visible from the back of many systems because it contains the
power-cord receptacle and the cooling fan.
General information
Project pages for car PC power supplies
Power connector pinouts
Many applications require current sources rather than voltage
sources. Current source provides a constant current to the output. This current does not
depend on the output voltage. An idea current source is a high output impedance device: it
will supply current, but does not show in other ways on the load circuit.
When you need a low-current source, using a linear regulator is a
typical approach. When you need a high-current source, using a linear regulator is
inadvisable, because of the high power dissipation in the series resistor. To solve the
wasted-power problem, you can use a switch-mode regulator.
- 40V current
source operates from -40 to +85°C - wide-output-current range sources that
accommodate a wide supply and temperature range, based on LM317
- Current
source has high output impedance - composite 10-mA current-source configuration that
has a compliance voltage of 5 to 42V, a set-current error of less than 1% and an output
impedance of greater than 100 megaohms
- Digital
current source is nonvolatile - Digitally programmable current sources that feature
automatic trimming and retain the setting despite power-down cycles are useful in
applications such as RF- and laser-communications drivers. This circuit is particularly
suited for setting the drive current for the optical pump in widely tunable VCSELs
(vertical-cavity surface-emitting lasers).
- High-speed
regulator makes great current source - bandwidth of this circuit measures more than 1
MHz, only the selected MOSFET and the ratings of the input supply's bypass capacitors
limit the voltage compliance
- L200
Regulator Circuit - easy to build a power supply with one single L200 IC, offers a
variable current limit of up to 2 A, as well as voltage regulation
- Precision
current sink costs less than $20 - simple active load circuit for current from 1 mA to
1A and voltage from 3 to 40V
- Programmable
current source powers charger - digitally programmable current source capable of
sourcing currents as high as 2.55A
- Simple
scheme keeps current drain constant - It is sometimes advantageous to keep the overall
current consumption of an electronic device constant. This circuit outptu variable current
to 5V load and maintains a constant current of approximately 102 mA in the power supply
input.
- Switching
regulator forms constant-current source - When you need a high-current source, using a
linear regulator is inadvisable, because of the high power dissipation in the series
resistor. To solve the wasted-power problem, you can use a switch-mode regulator. This
circuit uses an LM2576 adjustable regulator. It needs only a few external elements and has
an adjustable sensing input, which you use for controlling the output current.
- Variable 3 -
24 Volt / 3 Amp Power Supply - regulated power supply can be adjusted from 3 to 25
volts and is current limited
- Variable Power Supply
- based on versatile L200 voltage regulator, independent voltage (3-15V) and current
(10mA-2A) limits
Normal batteries have generally 1.5V per cell voltage (except some
Lithium cells which have 3V voltage). The batteries which have higher voltage output are
built genrally from many 1.5V cells in series all put inside same "case".
Rechargeable batteries have generally somewhat different lower
voltages and capacity than their their "only once usable" counterparts. Normal
alkalines are 1.5V each, but Ni-Cd batts are only 1.2V each. If you use four of them for
instance, you only get 4.8V instead of 6V. You can make up for it by adding a cell for
each four cells, so five cells will give you 6V. That's probably why some equipment
instructions don't allow them. Another reason could be that NiCd batteries have enormous
short-circuit current capability (easily tens of ampreres or more) compared to many
traditional batteries (causes greater risk of fire in case of short circuit). NiCd
batteries are easy to charge at slow charge mode. Just apply a charging current, typically
around 50 mA for 500mah cells, for 12-14 hours to change them. It does not hurt the
batteries if you charge the batteries at the current with somewhat longer times (even few
times longer) than needed. When batteries are are charged after they are full, the applied
power is converted to heat, so NiCd batteries should start to become warm then. Some will
say sinking C/10 (50mA for 500 mAh battery) indefinately into NiCd is acceptable but this
is not a recommended practice. NiCd batteries can also be charged faster with special
"smart chargers" which use controlled higher current to the batteries until they
are charged and stop this current when batteries are full (the charger has special sense
circuitry for this). Exercise extreme precaution when handling and testing NiCd batteries.
NiCd batteries include some amount of cadmium (Cd), which is dangerous material for
enviroment. Do not throw NiCd batteries away with your trash. You should bring those
batteries to recycling. When discharging NiCd battery packs be cautious about
over-discharge. Individual NiCd cells can go to zero volts but in a battery pack letting
them drop below 1V each may reverse and ruin a weak cell since they are in series.
In some applications NiCd batteries are replaced with higher
capacity NiMH batteries. Those batteries have pretty much similar characteristics to NiCd
(except that they need somewhat different charger). NiCad and NiMh cell voltages are
identical. There is some difference at end of charge and used by sophisticated chargers.
NiMh are sensitive to overcharge. NiMh should be preferably be always charged with
"smart chargers" designed to charge NiMh batteries. NiMh batteries can also be
charged with constant current C/10 (50mA for 500 mAH cell) current, but you should avoid
excessive overcharge because this will shorten battery life. Compared to Nicad NiMh are
nearly twice the capacity, can be recharged from any level, selfdischarge more tha twice
as fast, have about half the full cycle number life, and are not as robust when charging.
Many new small gadgets like cellular phones use Li-ion batteries.
Li-ion batteries have a high energy density. Exercise extreme precaution when handling and
testing Li-ion batteries. Do not short circuit, overcharge, crush, drop, mutilate,
penetrate, apply reverse polarity, expose to high temperature or disassemble them. Only
use the Li-ion battery with the designated protection circuit (cellular phone batteries
usually have this). Abuse of Li-ion can cause "explosion" like happening,
because in short circuit the case temperature can get very high and the electrolyte inside
Li-ion battery is highly flammable.
Car batteries are built are lead acid cells. They have a cell
voltage of around 2 volts (means 6 cells in series makes 12V battery). Normal 12V car
battery is designed to be quite robust. It can be carged with almost any reasonably
current limited constant voltage source of around the nominal voltage of the battery (for
example 13.5V for 12V car battery). Car batteries are built for heavy currents but DO NOT
deep discharge them, only shallow discharge. If you repeatedly run a car battery down to
much below 50% of capacity you will seriously shorten its life. Warnings on car batteries:
Car batteries contain dangerous acid hare heavy, so handle carefully. Charging car
batteries can generate highly flammabble hydrogen, so it is best to charge those only in
well ventilated spaces. Car batteries have very large short circuit current (hundreds of
amperes), so do not short circuit them (a fuse near battery terminal is essential for
safety to avoid wire fires in short circuit happens).
There are also other types of lead acid cells than car batteries.
Some are designed for deep discharge use and some for some other applications. Generally
lead acid batteries don't like to be discharged below 1.67 volts per cell (10V for a 12V
battery) and their full capacity can only be extracted if the load current is something
like C/10 or C/20 (where C is the barrery capcity in Ah and resulting current is in A).
Short list of most common battery characteristics:
- Lead Acid: most economical for larger power applications where weight
is of little concern (cars, boats, wheelchairs, emergency lighting, UPS systems), low
energy density (30-50 Wh/kg), available in low cost versions, cell voltage 2V, voltage
limiting rather than current limiting is used for charging
- Sealed lead acid (SLA,Gelcell): maintenance-free lead acid battery
with electrolyte in moistened separators, enclosure is sealed, used for wheeled mobility,
typical charge times are 8 to 16 hours, must always be stored in a charged state, 200 to
300 discharge/charge cycles
- Nickel Cadmium (NiCd): mature and well understood technoogy used in
chargeable batteries used in many applications (power tools, two-way radios, video
cameras), standard against which other batteries are usually compared, not very good
energy density (45-80 Wh/kg), cell voltage 1.25V, life cycle 1000-1500 charges
- Nickel-Metal Hydride (NiMH): higher energy density (60-120Wh/kg)
compared to the NiCd at the expense of reduced cycle life, no toxic metals, used in mobile
phones and laptop computers, cell voltage 1.25V, life cycle 300-500 charges
- Lithium Ion (Li-ion): fastest growing battery system, high-energy
density (110-160 Wh/kg) and lightweight, technology is fragile and a protection circuit is
required to assure safety, applications in notebook computers and cellular phones, cell
voltage 3.6V, life cycle 500-1000 charges
- Lithium Polymer (Li-polymer): uses a dry solid polymer electrolyte,
cell thickness measuring as little as one millimeter, suffers from poor conductivity (high
internal resistance)
- Lithium Ion Polymer (Li-ion polymer): uses a combination of dry
polymer electrolyte combined with some gelled electrolyte, ultra-slim geometry, high
energy density (100-130 Wh/kg), used in mobile phones, cell voltage 3.6V, life cycle
300-500 charges, promotional reasons most battery manufacturers mark this kind of battery
simply as Li-polymer
- Reuasable Alkaline: Special alkalinen battry which can be charged few
times (energy density 80 Wh/kg), cell voltage 1.5V, life cyle around 50 cyled of 50%
charge/recharge
General battery information
General charging circuits
Battery chargers for NiCd batteries
- Battery
charger indicates rate of charge - a single LED indicates whether the battery charger
s delivering a trickle charge or a fast charge, cricuit designed to charge 2-14 cells
- Constant
Current Nicad Charger - The schematic for this charger is pretty simple. You can
charge from 1 to 20 +/- nicads at a constant current of from 20 to 200 ma +/-.
- Make
Your Own Simple Rx/Tx Battery Charger with Peak Detect - This circuit is designed to
peak charge Rx and Tx batteries. It's programmed for a C/2 charge rate for 250mAh and
500mAh batteries (charge currents of 125mA or 250mA). It'll charge Rx from 12V at the
field, Tx from a 15V supply (like a car w/engine running). Use a 15-18V supply to charge
at home (you should be able to find wall cubes with this rating). It is based on a Maxim
IC, the MAX713.
- Ni-Cd Batteries
Charger - A very basic circuit that takes approximately 12-15 hours of charge
AA-batteries at 50mA charging current.
- Nicad
Battery Charger - uses a single transistor as a constant current source
- NiCd or
NiMh battery charger - This charger can be used for AAA, AA and Baby C batteries. This
battery charger is based on MAX712/MAX713.
Li-ion battery chargers
- Charge
Li-ion batteries from ac line voltage - converts energy from 120V ac to a regulated
voltage or current as necessary to charge two Li-ion cells in series
- Supply
derives 5 and 3.3V from USB port - This circuit derives its power from a USB port and
produces 5 and 3.3V supply rails for portable devices, such as digital cameras, MP3
players, and PDAs. The circuit allows the port to maintain communications while, for
example, charging a lithium-ion battery. IC2 boosts the battery voltage, VBATT, to 5V, and
IC3 buck-regulates that 5V output down to 3.3V.
Lead-acid battery cargers
Combined power supplies and batery chargers
Battery discharging circuits
Battery backup circuits
Battery protection
Battery status sensors
Normal battery chargers
Bascially all types of alkaline cells can be recharged, although the
battery manufacturers discourage this (dangers of overcharging and battery leaking). You
will need a special charger for charging alkaline cells (normal NiCd chagers are not
suitable for this). There are some special alkaline cells nowadays which chan be charged
better than normal alkaline cells. The best practice is not to discharge completely the
cell or battery but rather to give a short charge often. Do not attempt to recharge a
totally discharged cell or a cell showing even the slightest sign of damage.
- Alkaline Charger
- This circuit was specifically designed to recharge alkaline cells. It will take around 1
day for a discharged AA cell or 9V battery and up to several days for a large D type cell
to carge.
Other battery circuits
Have you ever wanted to run a TV, stereo or other appliance while on
the road or camping? Well, a power inverter should solve that problem. An inverter is an
electrical device that converts 12-volt power into mains power (120V 60Hz AC or 230V 50 Hz
AC typically). Typically you run an inverter off of your car's battery or off of a
deep-cycle battery that you buy specifically to power the inverter. An inverter is usually
a very easy and inexpensive solution to get mains power where it is not normally available
if you can keep your power demands in the 200-watt range.
With around 300 watts of continuous power inverter you can run items
like desktop computers, monitors, full size fax machines, battery chargers and AC adapters
for notebook computers, cellular phones, camcorders, small power tools, drills, mid-sized
TVs, soldering guns, and a variety of rechargeable equipment on the road. If you have a
higher power inverter, you can run more devices or more powerful devices. With a lower
power converter you can use only devices which use less power. Power inverters are also
very useful in solar power system which generally use low voltage batteries (usually 12V
DC) to be able to run mains powered devices in them.
The three most common outputs for inverters are square wave,
modified sinewave (sometimes called a quasi sinewave), and sinewave outputs. Most devices
with variable speeds such as electric drills, or devices with chargers such as cordless
drills or screwdrivers, can behave irrationally when operating with modified sine or
square wave inverters. Small wall based chargers (called wall warts) can have overheating
problems with modified sine or square wave inputs. Some computers and stereo equipment use
switching power supplies that utilize SCR’s and Triacs as well. These pieces of
equipment may experience the same troubles with non-sinewave power. True sine wave output
allows connected loads and equipment to operate the same as they would from utility
supplied power. Unfortunately the true sine wave output inverters are more expensive than
the ones which use square wave or modified sinewave.
Generally you can buy a small 150- or 300-watt quasi-sine-wave
inverter for about $50. Higher power or true sinewave models cost generally more.
An Uninterruptible Power Supply (UPS) is a device that sits between
a power supply (e.g. a wall outlet) and a device (e.g. a computer) to prevent undesired
features of the power source (outages, sags, surges, bad harmonics, etc.) from the supply
from adversely affecting the performance of the device. UPS devices generally consist of
some form of internal battery, inverter and intelligent switching electronics. When normal
mains power is available, it is supplied to the devices connected to UPS. When mains power
is not available, the devices connected to UPS output are powered by the inverter circuit
inside the UPS. UPS devices aren't designed to let you keep working for a long period of
time after power outage; they're designed to give you enough time to shut your system down
in the normal manner.
NOTE: Most of the circuits below have square wave output and are not
suitable for driving sensitive electronics equipments. The AC from those inverters can
damage some equipments connected to them.
General articles
Circuits
- 24 Volt DC to
110 Volt AC Power Inverter - Converts the power from two 12 volt batteries to AC to
power a drill or whatever
- 5W Inverter - A
single transistor is all you need for this simple inverter. The main aim of this circuit
is to provide a suitable supply for all kind of low power battery chargers that normally
connect to the mains such as mobile phones, electric shavers, etc, even an electronic neon
light rated at 5W.
- Basic 200 W power
inverter - 12V DC to 110V 60 Hz AC, up to 200W continunous, square wave output
- Building a dc to ac
converter - Otherwise known as a dual axis drive corrector, this unit is intended to
provide 240 volts/50 Hz (or 120 volts/60 Hz with minor modifications) for a right
ascension (ra) drive and a reversible declination motor. The supply requirement is from 11
to 16 volts d.c. at 500 mA. The overall output frequency is adjustable from 47.5 Hz to
52.5 Hz or from 40 Hz to 60 Hz on the remote unit. This frequency is stabilised against
voltage or temperature change.
- DC/AC
inverter - 12V DC to 110V AC
- DC
to AC power inverter - convert 12V DC to 120V AC, based on SCRs and FETs
- Inverter
- takes 12 VDC and steps it up to 120 VAC
- Inverter
offers design flexibility - works from a 12V car battery and produces mains voltage
with closed-loop voltage regulation
- SCR Inverter -
outputs 300V 400Hz, waveform is vaguely sinusoidal, 5W output power
- The
I2K Power Inverter - This circuit is a 2kVA 12VDC to 120VAC inverter for power backup.
This description of the inverter is preliminary and incomplete.
- Uninterruptible
Power Supply (UPS) FAQ - This is a FAQ document on Uninterruptible Power Supplies. It
is intended to provide a starting point for those people that want to find out what they
are, what they do, and what's available. Most of this document is very US-centric. The
power numbers, companies and services all emphasize US consumer needs.
- Uninterruptable
Power Supply Reference Design - Application note from Microchip
- Uninterruptible
Power Supply Types - Most people know that UPSes exist, but many seem to think that
there is just one kind of device that goes by that name. In fact, there are several
different major designs in use for UPS models. Those who sell these devices share much of
the blame for this situation, because too often, the different kinds of UPS are all called
the same, generic name.
- UPS Semiconductor
Technologies
- 220V Mains Monitor
- With this circuit you will be able to monitor the quality of the mains. There are 4
distinct sections, each supervising a parameter pertinent to the quality of the supply
line. There are sections for noise, spikes, voltage and flutter.
- Circuit
breaker monitors leakage current - This residual-current circuit breaker continuously
monitors the supply lines for any leakage current and immediately disconnects the supply
if necessary.
- Circuit
breaker has programmable delay - this circuit provides overload and short-circuit
protection to a 5V power-supply output
- Circuit
protects against ac-line disturbances - operates by switching off the power supply
upon detection of undervoltage or overvoltage conditions
- Circuit
safely applies power to ICs - Supervisory circuits normally monitor a microprocessor's
supply voltage, asserting reset to the IC during power-up, power-down, and brownout. In
this way, the circuit ensures that the supply voltage is stable before the microprocessor
boots, thus preventing code-execution errors. This circuit works so that is connect power
to sensitive ICs only when they are at safe level.
- Circuit
senses high-side current - The accurate, high-side, current-sense circuit does not use
a dedicated, isolated supply voltage, as some other schemes do.
- Comparator
detects failed telecomm supplies - detects when telecomm power supply's 48V output
drops below its nominal value, uses an isolated comparator to monitor two 48V telecomm
supplies (of either polarity)
- Current
limiter provides latch-up signal - current-limiting circuit both signals a latch-up
condition and prevents latch-up-induced overcurrent destruction of a CMOS IC or group of
ICs
- Current
limit protects power bus - protects a power bus from a load short within a guaranteed
2 µsec response time
- Detect
Fan Failure With A Single Transistor
- Double-ended
flashing voltage monitor using LM10 - can detect an over and under-voltage condition
and flash LED
- Electronic
fuse emulates fast- or slow-blow fuses - The electronic-fuse circuit in this article
combines the properties of a current transducer and a solid-state relay to disconnect low
power at preset levels. Using this circuit lets you avoid the bother of stocking and
replacing fusible links.
- Fuse Monitor / Alarm
- a simple way to see if a fuse has blown without removing it from its holder
- High-current
trip - electronic fuse circuit will quickly break the circuit when the current exceeds
about 50A
- Mains
power failure alert
- Microamps
monitor dual-supply batteries - low-power circuit monitors two 9V batteries in a
dual-supply configuration and turns on the Battery Low LED if either battery voltage drops
below its limit
- Monitor
high-side current without an external supply
- Optocoupler
extends high-side current sensor to 1 kV
- Overload and
reverse-current circuitry protects battery and load - there are numerous circuits can
protect against backward installation of batteries and other overcurrent-causing
conditions
- Over
Voltage Protection - describes crowbar technique that provides a useful defence for
fast over voltage spikes and transients that could cause damage to more sensitive
components
- Power-Supply
Failure Alarm - alarms with beep when mains power feed fails
- Protection
for your Electrical Appliances - very low-cost circuit to save your electrically
operated appliances from the effects of sudden tripping and resumption of mains supply,
this circuit switches off the mains supply to the load as soon as the power trips
- Simple
Current-Limiter And Power Switch Offer Overcurrent Protection
- Single LED
indicates two power states - uses a single bicolor LED to indicate both power-on and
blown-fuse conditions
- The fuse
monitor - a neon glow lamp indicates by remaining lit that the fuse is in order, by
blinking that the fuse has blown and by remaining off that there is no power
- The main
voltage monitor - main voltage monitor that is simply a lamp that glows when the main
voltage is present, designed for 230V AC, can be adapted to 110V AC operation
- Two-lead
solid-state breaker resets itself - simple dc circuit breaker can protect a power
supply from the ever-present screwdriver or even isolate a satellite's dual power system
from a short circuit in one subsystem
- +5v from RS-232
using LM78L05
- Advanced polarity
protection with MOSFETs - Advanced Power Switching and Polarity Protection for Effects
- A Simple
Capacitance Multiplier Power Supply For Class-A Amplifiers - A mentohd which providess
good noise filtering but no actual voltage regulation
- Automaatti-sulake
- This is an automatic fuse circuit for 24V power. Thsi circuit uses transistors which
control an output relay. The text of this document is in Finnish.
- Circuit
combines power supply and audio amplifier - This circuit can helpful if you must
transfer dc power and audio over a pair of copper wires. The circuit uses only one IC, the
well-known LM317, a low-cost power-supply regulator. Using this chip, you can modulate the
adjustment-pin input with the audio signal from an electret condenser microphone,
connected between the output and the adjustment terminals of the IC.
- Clamping
circuit dissipates minimal power - quasi-linear regulator
- Drive
high-voltage varactor diodes from just 5V - how to connect two International Rectifier
(El Segundo, CA) PVI1050s photovoltaic-isolator ICs in series to provide a 20V tuning
drive for the varactor diode
- Electronic
Fuse for Power Supply - This circuit offers effective protection against overcurrent
in power supply with output voltage through to 45V DC and output current form 0.1A to 5A.
- High-Voltage EL Lamp
Driver
- Micropower,
10ppm/°C, +/-5v reference
- MOSFET
replaces switch - you can use a single-pole switch to turn a bipolar power supply on
and off without consuming extra power
- Power
switch provides soft start
- Quickly
discharge power-supply capacitors - A perennial challenge in power-supply design is
the safe and speedy discharge, or "dump," at turn-off of the large amount of
energy stored in the postrectification filter capacitors. If you let the capacitors
self-discharge, dangerous voltages can persist on unloaded electrolytic filter capacitors
for hours or even days. This design idea gives one alternative approach for faster
discharge than normal bleeder resistors provide.
- Rectification using a
Gyrator Circuit
- Series
Lamp Limiter - connect a 100W lamp bulb in series with the supply to the equipment
being repaired to avoid very nadty high short circuit current is something goes seriously
wrong, useful for power supply testing and repairing
- Smoke Detector Power
Supply - This power supply normally supplied power from AC mains power source thrpgh
transformer nad charges a battery. When AC mains power dissapears, the power is supplied
from the battery.
- Soft-Start Circuit
For Power Amps - This circuit reduces the current spike large transformers take when
switched on.
- Soft
Power On Tester for Amplifiers - The worst thing that can happen is that when you turn
an electronics device you are fixing on, it immediately pops a fuse - or worse yet a
valuable part you've just installed! If you don't have a variac with a current meter so
that you can make power on gradual, the next best thing is this widget. It can be whipped
up from parts in your local home supplies store.
- Time-delay
relay reduces inrush current - A transformer switching onto a line can sometimes cause
a circuit breaker to trip or a fuse to blow. This phenomenon occurs even if the
transformer presents no load, such as when the secondary is open. The problem arises
because of the heavy magnetizing inrush current in the transformer. This design solves the
problem in one way.
- Transistors
offer thermal protection for controller - You can use standard bipolar transistors to
implement a low-cost thermal-shutdown circuit for switched mode power supply.
- Transistor
latch improves on/off circuitry
- Versatile
power-supply load uses light bulbs - Improvising loads for bench-testing and designing
power supplies is often a frustrating and sometimes hazardous experience. Many electronic
loads are on the market but are usually expensive and of laboratory-type precision and
often represent overkill for the average designer. Incandescent light bulbs make excellent
loads, able to handle large amounts of power. Moreover, they come in small packages and
require no heat sinks. The drawback is that the resistance of an incandescent lamp changes
dramatically with the power input. A simple approach to this control problem is to
pulse-width-modulate a power MOSFET in series with the load.
- Voltage follower
with 1G ohm input resistance
