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Variable Power Supplies, Page 1
Power Supplies -- Main Page

Variable Power Supplies:   #-L     M-Z
Last Updated on: Monday, October 26, 2009 03:45 AM

 

Circuits Designed by Dave Johnson, P.E. :
  • VARIABLE ISOLATED AC VOLTAGE SPANS 0VAC TO 280VAC
    I designed and built this circuit about 25 years ago. It came in handy for many projects that were powered from 120 VAC, 240 VAC and 277 VAC. It provides complete isolation from the power line. It uses two 1:1 isolation transformers that are wired in parallel for the140vac range and in series for the 280vac range. The selector switch also diverts power to the appropriate output socket to avoid mishaps in sending the wrong voltage to the load. My home-built unit also included an AC volt and amp meter to monitor the output. However, this circuit only indicates the AC power connections.

 


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

1A Variable Regulated Power Supply - A 'must-have' for the experimenter.  (electronic design 05/09)

230 Volt Dimmer - FAIR WARNING THIS SITE HAS ANNOYING POP UPS (added 2/03)

3V supply delivers 12V p p to piezo speaker - 10/16/03 EDN-Design Ideas: Low-profile piezoelectric speakers can provide quality sound for portable electronic devices, but y require voltage swings greater than 8V p-p across  speaker element. Yet, most portable devices include only a low-voltage power source,.....(design idea added 1/05)

5V Power Supply teams Low dropout regulator charge pump - 01/08/04 EDN-Design Ideas: Auxiliary power of 3.3V is replacing  5V auxiliary power that "silver boxes" supply in most computer systems, but some circuits still require a 5V supply. Such systems impose  messy task of creating a central 5V auxiliary supply from  3.3V auxiliary supply and n routing 5V power throughout  morboard.....(design idea added 1/05)

Add gain to an absolute value Amplifier - 08/22/02 EDN-Design Ideas: The absolute-value amplifier is a basic building block in test-and-measurement and signal-processing applications. The addition of a DPP (digitally programmable potentiometer) adds anor dimension, G (gain), to this key circuit. Because  gain is programmable, you can use  circuit as an absolute-value amplifier (G<1)or an absolute-value attenuator (G>1).....(design idea added 1/05)

ADE7758 Phase Dropout Detection for VAR Calculation - AN-750 Analog Devices Application Notes  (app note added 6/06)

Adjustable Power Supply (Aaron Cake) - well filtered variable1.2-30 volts at5 amps using LM338K (added 5/02)

Adjustable Power Supply using LM317 - voltage regulator for1.2V to35-Volt output voltages and up to1A load  (added 11/05)

Adjustable Voltage Motor Controller - One of the nice things about flying electric is you can test run your motor in the house, workshop, or in the yard and the neighbors won't complain. The problem is how to control the speed of the motor. One way is to use the plane, radio, and speed control with the motor in it. That's no fun! ....(electronic circuit added 4/05)

Cascoded stack yields multiple Voltages - 03/16/00 EDN-Design Ideas:.....(design idea added 2/06)

Circuit Adds foldback Current protection - 07/21/05 EDN-Design Ideas: Enhance three-terminal regulator with foldback oversight.....(design idea added 5/03)

Constant Current Battery Charger - A simple method of charging a battery from a higher voltage battery is shown in the circuit below to the left. Only one resistor is needed to set the desired charging current and is calculated by dividing the difference in battery voltages by the charge current. So, for example if 4 high capacity (4000 mA hour) ni-cads are to be charged at 300 mA from a 12 volt battery, the resistor need,....(circuit added 7/02)

Dual Power Supply (albert kreuzer) - Some brands of electrolytics have a small inductance which will cause the regulator ICs to oscillate. Use tantalum caps for C5/C6 to be sure (but also most normal electrolytic will work)….(electronic circuit added 4/05)

Dual power supply delivers 8A with no heat sinks - 03/30/00 EDN-Design Ideas: The circuit in Figure 1 is a high-current dual supply that provides 5 and 3.3V at currents as high as 8A. The circuit uses a fixed-frequency, two-output, current-mode synchronous-buck- controller.....(design idea added 2/06)

Dual Regulated Power Supply-PSU - (electronic circuit added 4/05)

Dual Voltage Regulator meets USB Power needs - 08/19/04 EDN-Design Ideas: This Design Idea stems from the limited availability of IC voltage regulators that can meet key USB-power specs, coupled with the need for turn-on sequencing and rise-time control at each output. As always, for PC-related designs, minimum cost is a primary motivation. USB specs require all loads to limit inrush current to less than 100 mA plus 50 µC of charge when powered.....(design idea added 1/05)

Easy Power Supply - (electronic circuit added 4/05)

High Current Power Supply - Since my page was first posted, I have received a number of emails asking about a high current power supply. I looked around, but couldn't find one that was suitable. So, I designed this. It is a linear supply, which might have a few of you rolling your eyes, but it takes very few parts, is simple to build and can supply huge currents. ….(electronic schematic added 11/08)

High Current Power Supply (Aaron Cake) - (electronic circuit added 4/05)

High Current Regulated Power Supply - (electronic circuit added 4/05)

High Current Regulated Supply - Current of LM317 voltage is increased by using an additional power transistors. ….(electronic schematic added 11/08)

High Current Supply uses Standard Three Terminal Regulator - 07/22/04 EDN-Design Ideas: This Design Idea implements a simple voltage regulator that delivers high output current. The basic idea is to parallel-connect multiple three-terminal regulators.....(design idea added 1/05)

Lantern Flasher/Dimmer - The electronic lantern control circuit adds high-efficiency dimming and flashing to an existing battery-powered lantern or flashlight or to a custom design.  For the car it makes a great lamp for changing a flat tire, back seat reading or emergency engine work.  The flasher mode ... (Tony van Roon's electronic design added 2/06)

Lantern Flasher/Dimmer (techlib) - The electronic lantern control circuit (fig. 1) adds high-efficiency dimming and flashing to an existing battery-powered lantern or flashlight or to a custom design. For the car it makes a great lamp for changing a flat tire, back seat reading or emergency engine work. The flasher mode is useful for warning other drivers....(circuit / schematic design added 6/06)

Lantern Flasher/Dimmer (tomzi.geo) - Basically a high-efficiency dimmer, but can also be used as a flasher. In dimmer mode, the LM358 (dual op-amp) is wired to send pulses at a constant frequency. By adjusting the width of these pulses, brightness of the bulb is controlled. In flasher mode, the same potentiometer....(circuit / schematic added 2/03)

LM317 Regulator with Pass Transistor - (electronic schematic / circuit added 4/02)

LM317 variable power supply - A truly timeless circuit. LM317 is a versatile and highly efficient 1.2-37V voltage regulator that can provide up to 1.5A of current with a large heat sink. It's ideal for just about any application. This was my first workbench power supply and I still use it.  Since LM317 is protected against short-circuit, no fuse is necessary.....(added 10/05)

LM317 Variable Voltage Regulator - (electronic schematic / circuit added 4/02)

LM317T Variable Voltage Regulator - The LM317T is a adjustable 3 terminal positive voltage regulator capable of supplying in excess of 1.5 amps over an output range of 1.25 to 37 volts. The device also has built in current limiting and thermal shutdown which makes it essentially blow-out proof.,.... (added 05/06/07)

Low Voltage High Current Time Delay Circuit - (circuit added 7/02)


           
Variable Power Supplies:   #-L     M-Z
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