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

 

Last Updated: November 21, 2017 05:46 AM

Circuits Designed by Dave Johnson, P.E. :

A Current Transformer used to Harvest Energy - Energy harvesting is all the rage these days.  With some modern electronics, information from low power sensors can be sent to a distant data collection point using a low power RF transmitter.  To power these remote sensors, various energy sources can be . . . Hobby Circuit designed by Dave Johnson P.E.-January, 2010

AC Current Monitor - This circuit uses a small AC current transformer from Magnetek to produce an isolated voltage proportional to the AC current in the primary winding.  The transformer contains a single turn primary with a low 0.001-ohm resistance.  It can easily handle 30 . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

AC to DC (240v to 5v)Power Supply - This is simple way to power some 5v logic from a 240vac source.  If a 120vac power adapter is used, the circuit will also work for 120vac power lines . . . Hobby Circuit designed by David Johnson P.E.-February, 2002

AC to DC 18V Power Supply - This is a classic linear power supply which produces a regulated 18v, rated at about 1 amp . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

AC to DC Power Supply requires Low Power - Last month I showed how to use a small common mode choke as a fully isolated transformer and a 130v sidac to generate about 100mw of DC power from the AC line.  This second circuit still uses the same inexpensive tiny off-the-shelf 5mH common mode filter coil with a split bobbin as a high frequency transformer but uses two SCRs instead of a sidac to discharge a capacitor . . . Hobby Circuit designed by David Johnson P.E.-November, 2011

AC/DC relay from Charge Coupled MOSFET - 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 . . . Hobby Circuit designed by David A. Johnson P.E.-October, 2005


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

A 12 volt Inverter-Very Basic type-  This circuit will provide a fairly stable "Square Wave" Output Voltage.  Frequency of operation is Mainly determined by the 220 uF Feedback Caps.  Currently about 60 Hz.  Various "off the shelf" transformers can be used. __ Designed by G.L. Chemelec

A Current Transformer used to Harvest Energy-  Energy harvesting is all the rage these days.  With some modern electronics, information from low power sensors can be sent to a distant data collection point using a low power RF transmitter.  To power these remote sensors, various energy sources can be . . . Hobby Circuit designed by Dave Johnson P.E.-January, 2010

A Simple Circuit Inverter-  This circuit will provide a fairly stable "Square Wave" Output Voltage.  Frequency of operation is Mainly determined by the 220 uF Feedback Caps.  Currently about 60 Hz.  Various "off the shelf" transformers can be used. __ Designed by G.L. Chemelec

A Simple Circuit Switching Power Supply-  A Versatile and useful supply to Experiment with, Good for the Beginner to learn.  This is Direct 110 VAC input. __ Designed by G.L. Chemelec

A small power supply for universal use based on an LM317 adjustable regulator-  This project describes a little power supply, based on a LM317, adjusteable from 1.25 to 30 V, delivering approx.1 Amp.  Yet another nice to have building block :-) __ Designed by Alexander C. Frank, aka Ajarn Changpuak

A Transformerless Power Supply-  Power Supply Circuits:  This circuit will supply up to about 20mA at 12 volts.  It uses capacitive reactance instead of resistance - so it doesn't generate very much heat.  The circuit was designed to provide a cheap, compact power supply for CMOS logic circuits that require only a few milliamps.  The logic circuits were then used to control mains equipment, using an optically-isolated TRIAC. __ Designed by Ron J.

A Variable power supply with adjustable current limiting-  A Variable power supply with adjustable current limiting - new design! 0-14V output up to 5A current. __ Designed by Steven Weber, KD1JV

A Very Basic 12 volt Inverter-  This circuit will provide a fairly stable "Square Wave" Output Voltage.  Frequency of operation is Mainly determined by the 220 uF Feedback Caps.  Currently about 60 Hz.  Various "off the shelf" transformers can be used. __ Designed by G.L. Chemelec

AC Current Monitor-  This circuit uses a small AC current transformer from Magnetek to produce an isolated voltage proportional to the AC current in the primary winding.  The transformer contains a single turn primary with a low 0.001-ohm resistance.  It can easily handle 30 . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

AC Power Meter-  If you would like to save electric energy, you first of all need to measure the AC current flowing through your appliances.  AC line voltage times the measured current value gives the power.  Build an AC power meter with a current transformer as shown in the schematic given above. __ Designed by MINOWA, Makoto  7N3WVM

AC to DC (240v to 5v)Power Supply-  This is simple way to power some 5v logic from a 240vac source.  If a 120vac power adapter is used, the circuit will also work for 120vac power lines . . . Hobby Circuit designed by David Johnson P.E.-February, 2002

AC to DC 18V Power Supply-  This is a classic linear power supply which produces a regulated 18v, rated at about 1 amp . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

AC to DC Power Supply requires Low Power-  Last month I showed how to use a small common mode choke as a fully isolated transformer and a 130v sidac to generate about 100mw of DC power from the AC line.  This second circuit still uses the same inexpensive tiny off-the-shelf 5mH common mode filter coil with a split bobbin as a high frequency transformer but uses two SCRs instead of a sidac to discharge a capacitor . . . Hobby Circuit designed by David Johnson P.E.-November, 2011

AC/DC Bike-Powered Generator System-  An exercise bike is fitted with a permanent DC magnet motor, which, charges a 12VDC lead-acid automotive battery.  This battery can be used to directly drive DC loads or can be fitted with an AC inverter to drive regular house-hold loads.  The system is interfaced through the PC to allow data-logging and monitoring of both instantaneous current, voltage and power along with accumulated power. __ Designed by Greg Miller

AC/DC relay from Charge Coupled MOSFET-  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 . . . Hobby Circuit designed by David A. Johnson P.E.-October, 2005

Active Power Zener-  Schematic only. __ Designed by Tony van Roon  VA3AVR

Adjustable Voltage Regulator-  Many amateurs have stopped by their local Radio Shack store and have noticed the famous LM317T adjustable voltage regulator.  But, did you know that all voltage regulators are adjustable? Yes, any IC voltage regulator can be adjusted to a higher voltage than its fixed voltage by just adding a couple of resistors __ Designed by Radio Amateur Society of Norwich

Alternative power source for Magellan GPS receivers-  This GPS receiver is powered by 2 AA batteries.  They are only strong enough for the GPS to stay on for about two hours, and this seems like quite a waste.  I would like to be able to use a larger battery, and sometimes even an AC adapter. __ Designed by Ryan Janzen

Amperage Booster for 78xx's-  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

Amplified Zener -  This circuit above uses a 13 volt zener diode, D2 which provides the voltage regulation. Aprroximately 0.7 Volts are dropped across the transistors b-e junction, leaving a higher current 12.3 Volt output supply. This circuit can supply loads of up to 500 mA. This circuit is also known as an amplified zener circuit __ Designed by Mick Devine

An Output Adjustable Flyback Converter-  A high voltage step-up DC power supply using adjustable flyback conversion. __ Designed by Andy Collison

AN132 - Fidelity Testing for A to D Converters-  Linear Technology AN132 __ Designed by Jim Williams - Oct 1st, 2011

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

AN-60-004  Ultra-Linear 50W Amplifiers 20-512MHz LZY-1-  AN-60-004 App Note__ MiniCircuits.com

AN-60-005  Ultra-Linear 32W Amplifiers 500-1000MHz LZY-2-  AN-60-005 App Note__ MiniCircuits.com

AN-60-009  High IP3, wide band, balanced linear power Amplifier HELA-10-  AN-60-009  Application Note __ MiniCircuits.com

Artificial ground to transform an Unipolar Power Supply into a Bipolar Power Supply-  The Approach used here is just an active Voltage Divider.  The GND of the Output just has to be centered between the positive and the negative Supply.  This can be achieved using a Power OpAmp such as the L149 ( 4A) or the L165 ( 3A) or any equivalent type being available at your local hardware store.  The Schematics below shows how to wire __ Designed by Alexander C. Frank, aka Ajarn Changpuak

AT PC Power Supply 1-  Schematic only, no text included__

AT PC Power Supply 2-  Schematic only, no text included__

AT PC Power Supply 3-  Schematic only, no text included__

AT PC Power Supply 4-  Schematic only, no text included__

AT PC Power Supply 5-  Schematic only, no text included__

Automatic 9-Volt NiCad Battery Charger-  BR1 can be a bridge rectifier or four diodes (10A) with a 100 PIV rating.  A 10, 000uF/50V electrolytic capacitor completes the filtering of the 28.8V.  Yep, C1 is a real clunker.  You can use larger if you like, just watch it when you power up.  Without a 'power-up' delay circuit of sorts it will probably blow-up the 723 if the capacitor (C1) is too-large. __ Designed by Tony van Roon  VA3AVR

Automobile Interior Light Fader-  This circuit is similar to the fading eyes circuit above and is used to slowly brighten and fade interior lights of older cars.  The circuit is based around the LM324 low power OpAmp which draws around 3mA of current, so it won't bother the battery if left connected for extended periods __ Designed by Bill Bowden

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AC to DC Converters / Linear Power Supplies: 
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