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Power Supplies: AC to DC Converters / Linear
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Power Supplies -- Main Page

 

Last Updated: December 02, 2017 05:07 AM

Circuits Designed by Dave Johnson, P.E. :

Battery Eliminator - If you use a 1.5v or a 3v battery powered MP3 player for long periods of time, you may get tired of constantly changing batteries.  Some older players do not work will NiMH
rechargeable batteries so changing out batteries can get expensive.  The circuit be. . . Circuit by David Johnson P.E.-June, 2005

Capaciatance-Based Touch Switch - This is another capacitance based touch on/touch off switch, which can control power to a 200 watt 240vac load . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2002

Caps Provide Voltage Boost to Series Regulator - This circuit adds some capacitors and diodes to a traditional transformer type series regulator circuit to extend the normal operating range.  It can insure regulation during low line voltage conditions or it can squeeze a few more watts out of a plug-in-the-wall power adapter power supply. . . Circuit by Dave Johnson P.E.-January, 1998

Charge Coupled MOSFET Relay #2 - This circuit acts as an AC/DC relay with a rating up to 50 volts peak and up to 10 amps of current.  The differential oscillator supplies voltage to the gates of the two FETs with good isolation will drawing only 1.5ma of current. . . Circuit by David A. Johnson P.E.-October, 2005

Circuit Eliminates 9v Battery - If you use 9v battery powered devices for long periods of time, you may get tired of constantly changing batteries.  The circuit below can be wired into any 9v battery powered device, drawing power from an external AC to DC power adapter.  I designed the c . . . Hobby Circuit designed by Dave Johnson P.E.-December, 2009

Circuit Protects from Battery Polarity Reversal - This simple circuit can protect a sensitive electronic circuit from an accidental connection of a battery with a reversed polarity.  The N-channel FET connects the electronic device to the battery only when the polarity is correct.  The circuit shown was. . . Circuit by David Johnson P.E.-March, 2002

Classic Plus & Minus DC Power Supply - This is a classic example of a regulated DC power supply that produces both a positive 15v and a negative 15v from a 20vac wall adapter. . . Circuit by David A. Johnson P.E.-October, 2005

CMOS Schmitt Trigger IC Makes VCO - By changing the supply voltage fed to a classic 4584 Schmitt trigger type oscillator, the oscillator frequency can be changed over a range of 50:1.  A 74HCU04 inverter is used at the output of the 4584 to maintain a constant TTL logic level signal. . . Circuit by David Johnson P.E.-December, 2002

Convert AC to DC signal with is Full Wave Rectifier - This is a classic circuit that can accurately convert an AC signal to DC.  Using a LF412 high speed dual op amp, this circuit will rectify any signal up to about 100KHz with a minimum amplitude of about 50mv peak to peak.  At 40KHz the input signal can be . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006


Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

Basic 78xx series regulator mains power supply-  Everyone needs a power supply.  This simple one shows the general principles.  The first step is to select a transformer suited to your need.  The primary should be for the correct mains voltage in your country ( 120V in the US, 240V in most of the rest of the world). __ Designed by © 2009-2014 Hans Summers

Basic UPS Power Supply-  Regulated DC power supply, short circuit safe, and with current limiter.  This PSU has been especially designed for current-hungry ham radio transceivers.  It delivers safely around 20Amps at 13.8V.  For lower currents, a separate current limiting output, capable of 15ma up to a total of 20A has been added.  Let us see what we have got here.  The power transformer should be capable to deliver at least 25A at 17.5 to 20V.  The lower the voltage, the lower power dissipation. __ Designed by Bob

Battery Charger, Current & Voltage Regulated for Sealed Lead Acid batteries-  Current and Voltage Regulated for Sealed Lead Acid types __ Designed by G.L. Chemelec

Battery Eliminator-  If you use a 1.5v or a 3v battery powered MP3 player for long periods of time, you may get tired of constantly changing batteries.  Some older players do not work will NiMH
rechargeable batteries so changing out batteries can get expensive.  The circuit be. . . Circuit by David Johnson P.E.-June, 2005

Battery Low Voltage Beeper-  This circuit provides an audible and visual low voltage warning for 12V battery powered devices.  Idle current: 6ma Low Voltage Warning current: 15ma. __ Designed by G. Forrest Cook

Battery Voltage Monitor-  R1 controls the trip-point of the circuit.  adjust it accordingly.  to reverse the logic ( have the LED light up when the battery has at least X amount of power,) connect the LED to ground through R4. __ Designed by Andy Wilson

Battery voltage Monitor using an LM358 op-amp-  This circuit is used to monitor the battery voltage, using a bi-color LED to indicate the state of the battery.  When the LED is "GREEN" the battery voltage is above 11.9 volts.  When the LED is "YELLOW", the battery voltage is between 11.9 and 11.5 volts.  When the LED is "RED" the battery voltage is below 11.5 volts.  You can of course, modify the trigger points by using the trimmer resistors and/or changing the value of the dropping resistors in the divider. __ Designed by Steven Weber, KD1JV

BattMan II: Build a Computer Controlled Battery Manager-  BattMan II is a computer controlled battery manager, intended for typical rechargeable batteries used by R/C and electronics hobbyists, as well as various consumer product batteries. __ Designed by Stefan Vorketter

Bench power supply-  Back before we had computers to occupy all our time, my brother and I were always tinkering with motors and electronic junk and such.  This required electrical power, and good power supplies were hard to come by, so we each ended up building our own.  We had few parts and lots of time, so we each ended up taking apart and rewinding transformers at one time or another - I rewound the primary of a 220V transformer (from Germany) for 110V, Matthias rewound, I think, both windings of a transformer to convert it to 110V and put many taps in the secondary for various voltages. __ Designed by Markus Wandel

Bench power supply with buck converter with a linear afterburner-  This project describes a power supply, fully controlled by a microprofessor.  It is a cascaded approach, a step-down converter ( LT1074) generates an intermediate voltage which is then linear regulated by a TIP-3055.  So it is economical and low noise.  As it is digital, output voltage ranges from 0 to 25.5 V and 0 to 2.55 A.  You guess right.  Resolution is 0.1 V and 0.01 A. __ Designed by Alexander C. Frank, aka Ajarn Changpuak

Bidirectional Power Inverter-  08/02/01  EDN Design Ideas:  If you want to swap charge in either direction between unevenly loaded positive and negative battery buses, you need an inverting dc transformer.  One implementation is the symmetrical flyback converter shown in Figure 1.  The circuit __ Circuit Design by Tom Napier, North Wales, PA

Bipolar Power Supply with LM317t & with LM337t Controllable with Stereo Potentiometer-  Introduction LM317T and LM337T are well known and low cost adjustable voltage regulators with current limiting up to around 1.5A and power dissipation up to around 20W.It is useful to have bipolar...___ Electronics Projects for You

Breadboard supply-very Low dropout adjustable power supply-  This project details the design of a very low dropout adjustable power supply.  A good power supply is essential to electronic projects.  While there are many existing designs for adjustable power supplies, this one makes improvements that make it more useful for hobby designs. __ Designed by © Lucky Larry

Broken Charger-Connection Alert-  Detects if a device is not properly connected to its supply.  Suitable for battery chargers, portable appliance supplies etc. __ Contact Flavio Dellepiane, fladello @ tin.it

Buck Mode Switching Regulator for Solar Applications-  The purpose of a voltage regulator circuit is to take a variable input voltage and produce a steady output voltage.  Two common regulator types are linear and switch-mode.  Linear regulators are simple, but waste a lot of power in the process of regulating the voltage.  Linear regulators can be thought of as self adjusting series resistors.  Switch-mode regulators such as this one are much more efficient.  Switch-mode regulators convert DC input voltages to pulses of high voltage DC.  The DC pulses are used to charge a storage capacitor to the desired output voltage.  The voltage is regulated by varying the width of the DC pulse __ Designed by G. Forrest Cook

Build a 10 Amp 13.8 Volt Power Supply-  Sometimes amateurs like to home-brew their power supplies instead of purchasing one off the shelf at any of the major ham radio retail dealers.  The advantage to rolling your own power supply is that it teaches us how they work and makes it easier to troubleshoot and repair other power supply units in the shack.  It should be noted that there is no real cost advantage to building your own power supply unless you can get a large power transformer and heat sink for a super low price.  Of course rolling our own gives us the ability to customize the circuit and make it even more reliable than commercial units. __ Designed by N1HFX

Build a breadboard power Module for integrateds-  When I began building effects, I built directly on perfboard and sometimes, I had never before heard the circuit.  This LED to, on a few occasions, being disappointed with the sound and later de-soldering the valuable parts and throwing away the rest.  Other times, I would want to modify various components and would need the soldering iron for that as well. __ Contact holler @ runoffgroove.Com

Build a High Performance Voltage Regulator From Discrete Components-  While integrated circuits have become a staple of all modern circuit designs, it is still possible to build circuits without ICís and still achieve a high level of performance.  The circuit in Figure 1 is a high performance 5 volt voltage regulator built using discrete components that are readily available.  I have used no ICís and I have even substituted a 1N4001 in lieu of a zener diode.  The regulator output voltage varies by a mere .4% and has current limiting at 1.5 amps along with short circuit protection.  With the exception of thermal shutdown, this circuit closely matches the performance of the 7805 5 volt regulator IC. __ Designed by N1HFX

Build a Low Cost Thermal Peak Detection NiCd Charger-  The electric model aircraft and car industries have produced a bewildering array of field chargers for NiCd motor battery packs.  These range from simple 6 or 7 cell chargers consisting of a resistor and mechanical timer, to more complex chargers with peak detection, cycling, and the ability to handle 36 cell packs __ Designed by Stefan Vorkoetter

Build a Simple Circuit Rechargeable CMOS Battery-  Occasionally we come across a computer motherboard that seems to eat those CR2032 batteries every 4 to 5 months.  This is particularly frustrating because the computer works perfectly once booted but all the important BIOS settings are lost when the CR2032 battery fails.  This is very irritating if the affected computer will not boot up with the default BIOS settings.  I recently had a computer motherboard with this same irritating phenomenon.  A test revealed that the current drain __ Designed by Radio Amateur Society of Norwich N1HFX

Capaciatance-Based Touch Switch-  This is another capacitance based touch on/touch off switch, which can control power to a 200 watt 240vac load . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2002

Capacitor voltage stepper using 555 timer-  In conventional voltage multiplier circuits, AC is used to charge the capacitors network via diodes in one cycle and discharge in the other cycle in a particular combination, which thereby produces multiples of the peak voltage.  However, this circuit works on a different principle, and it is DC which is doubled.  It can be used to power low current circuits.__

Caps Provide Voltage Boost to Series Regulator-  This circuit adds some capacitors and diodes to a traditional transformer type series regulator circuit to extend the normal operating range.  It can insure regulation during low line voltage conditions or it can squeeze a few more watts out of a plug-in-the-wall power adapter power supply. . . Circuit by Dave Johnson P.E.-January, 1998

Car Converter - 12V to 9V-  To get a more precise output voltage, replace zener diode Z1 with 10V and R1 with a 1Kilo ohm potentiometer.  A Coolrib for Q1 is optional but highly recommended.  You can replace Q1 for a more robust type to get more output amps depending on your requirements.  Simple circuit to power your 9 volt cassette recorder and other stuff __ Designed by Tony van Roon  VA3AVR

Car Ignition Coil Driver from 110V AC-  This SCR Circuit can run a Car Ignition Coil in your home, to Obtain High Voltage. __ Designed by G.L. Chemelec

Charge Coupled MOSFET Relay #2-  This circuit acts as an AC/DC relay with a rating up to 50 volts peak and up to 10 amps of current.  The differential oscillator supplies voltage to the gates of the two FETs with good isolation will drawing only 1.5ma of current. . . Circuit by David A. Johnson P.E.-October, 2005

Charge Monitor for 12 Volt Rechargeable Lead Acid Battery-  A battery is a vital element of any battery-backed system.  In many cases battery is more expensive than system it is backing up.  Hence we need to adopt all practical measures to conserve battery life.  As per manufacturer's data sheets, a 12V rechargeable lead-acid battery should be operated within 10.  IV and 13.8V.  When battery charges higher than 13.8V __

Charge-Pump Voltage Doubler with Regulator-  Schematic only __ Designed by va3iul

Charger for gel lead acid batteries-  This high-performance circuit first quickly starts ( Tony van Roon's and holds) the charge at 2 amp, but as the voltage rises the current will consequently decrease.  When the current falls below 150mA, the charger automatically switches to a lower 'Float' voltage to prevent overcharging.  At the point that a full charge is reached, Q1 will bias and the LED will light. __ Designed by Tony van Roon  VA3AVR

Circuit Eliminates 9v Battery-  If you use 9v battery powered devices for long periods of time, you may get tired of constantly changing batteries.  The circuit below can be wired into any 9v battery powered device, drawing power from an external AC to DC power adapter.  I designed the c . . . Hobby Circuit designed by Dave Johnson P.E.-December, 2009

Circuit Offers Improved Active Rectification-  02/06/03 EDN Design Ideas:  Build an adjustable high-frequency notch filter - Rectifiers convert ac signals to dc.  You can combine a diode and a load resistor to create a half-wave rectifier, provided that the amplitude of the ac source is much larger than the forward drop of the diode (typically 0.6V].  Unfortunately, you can't use this method to rectify signals that are smaller than a diode drop __ Circuit Design by Reza Moghimi, Analog Devices Inc, San Jose, CA

Circuit Protects from Battery Polarity Reversal-  This simple circuit can protect a sensitive electronic circuit from an accidental connection of a battery with a reversed polarity.  The N-channel FET connects the electronic device to the battery only when the polarity is correct.  The circuit shown was. . . Circuit by David Johnson P.E.-March, 2002

Classic Plus & Minus DC Power Supply-  This is a classic example of a regulated DC power supply that produces both a positive 15v and a negative 15v from a 20vac wall adapter. . . Circuit by David A. Johnson P.E.-October, 2005

CMOS hex inverter generates low-distortion sine waves-  06/09/05  EDN Design Ideas:  Audio signal source uses hex inverter and handful of passives __ Circuit Design by Al Dutcher, West Deptford, NJ

CMOS inverters convert RF to digital signal-  01/05/06 EDN Design Ideas:  Hex-inverter-based design suits frequencies up to180 MHz __ Circuit Design by Francis Rodes

CMOS Schmitt Trigger IC Makes VCO-  By changing the supply voltage fed to a classic 4584 Schmitt trigger type oscillator, the oscillator frequency can be changed over a range of 50:1.  A 74HCU04 inverter is used at the output of the 4584 to maintain a constant TTL logic level signal. . . Circuit by David Johnson P.E.-December, 2002

Compressor-Mate-  protection for refrigerators, freezers and air conditioners __ Designed by Tony van Roon  VA3AVR

Considerations for Successive Approximation A ->D Converters-  Linear Technology AN17 __ Designed by Jim Williams - Dec 1st, 1985

Convert AC to DC signal with is Full Wave Rectifier-  This is a classic circuit that can accurately convert an AC signal to DC.  Using a LF412 high speed dual op amp, this circuit will rectify any signal up to about 100KHz with a minimum amplitude of about 50mv peak to peak.  At 40KHz the input signal can be . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

Converting a PCS Power Amplifier to 13cm Ham Radio Band-  Schematic only, no circuit description __ Designed by © 2001 - YO5OFH, Csaba Gajdos

Current booster for 78nn series voltage regulators-  Volt regulators such as the LM708, and LM317 series ( and others) sometimes need to provide a little bit more current then they actually can handle.  If that is the case, this little circuit can help out.  A power transistor such as the 2N3772 or similar can be used ( See the project on the 3-part variable power supply) __ Tony van Roon  VA3AVR

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AC to DC Converters / Linear Power Supplies: 
#'s - A         B - K        L - S       T - Z


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