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T13.8 Volt Power Supply   Schematics
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Modification to Astron   Modifications
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12 Volts to 5 volts   DC-DC Conversion
Repair your own power supply   Repair Your Own
Trace Side of Regulator   Reg PC Board
Finished View of Regulator   Assem. Reg PCB
Walk You Thru Repair   Repair Tutorial 1
Walk You Thru Repair   Repair Tutorial 2
RF Proof   RF Protection
Calculate Wire Size   Power Calculator
Ham Radio Links Page   Amateur Radio Links
Heat Sinks and Cooling   Heat Sinks Cooling
Crow Bar Over Voltage Protection   Crow Bar Circuit
Pass Transistor Schematic Configuration   Pass Trans. Config.
Output Transient Suppressor Network   Output Protection
Current Limit Resistor Network   Current Limiting
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Power Supply Load Tester.   Load Tester

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We have our own circuit board designed for Voltage Regulation.

The 723 voltage regulator and circuit are capable of regulating at a constant voltage, at a constant current. With current and voltage fold back. And with an additional circuit called a "Crow Bar" circuit, the 723 is capable of protecting the equipment, in the event of and over voltage at the output, being used on the power supply by blowing the AC input fuse, therefore, effectively removing the power source.

A schematic of the circuit, that we use, is on the "schematics" page. We have made a few modifications to it. Some are the addition of RFI prevention capacitors. You can use a 2n3055 for a driver transistor or what ever other NPN transistor that you may be using as pass transistors.

We do not supply small parts for your repair job of power supplies. There are just too many different applications that should be considered. is the place to order all your small parts. I have found this a place to obtain custom sized switches of all sorts of shapes and sizes. Get your measurements ready and give them a call. Don't be surprised to find that they can come up with an replacement on/off switch for your commercially made unit.

All parts including the high power .1 at 10 watt power resistors are quite reasonable from
We buy all our small parts from them.

Crow Bar circuit - Over Voltage Protector
NPN - Neg-Pos-Neg
RFI - Radio Frequency Inference

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