THIS PROCEDURE WILL HELP YOU CONSTRUCT A 12V AC/DC AND HV AC/DC POWER SUPPLY.

 

 
WARNINGS: HIGH VOLTAGE IS VERY DANGEROUS.  ARGUABLY EVEN MORE DANGEROUS IS MAINS VOLTAGE, BOTH OF WHICH WILL BE UTILIZED HERE.  BE VERY CAREFUL NOT TO COME INTO CONTACT WITH ANY OF THE ENERGIZED PARTS.  ALWAYS KEEP ONE HAND IN YOUR POCKET WHEN WORKING WITH HIGH VOLTAGE DEVICES.  ALSO SOLDERING IRONS ARE HOT, EVEN HOTTER THAN MCDONALDS COFFEE, IF YOU CAN BELIEVE THAT.


D
ESCRIPTION

MANY OF MY PROJECTS REQUIRE ELECTRICITY SO I NEEDED A POWER SUPPLY THAT COULD OUTDO THE 12V 'WALL WART' TRANSFORMERS I'D BEEN USING, AS WELL AS PROVIDE SOME HV DC FOR MY NITROGEN LASER.  THIS IS WHAT RESULTED. 

THE 12V 3A TRANSFORMER IS A RADIOSHACK STANDARD ITEM, AS ARE THE REST OF THE COMPONENTS, EXCEPT THE FLYBACK TRANSFORMER.  THE FLYBACK DRIVER IS THE AGE OLD '2N3055' DRIVER, WHICH ALMOST EVERY HV ENTHUSIAST HAS BUILT AT SOME TIME.  THERE ARE SEVERAL BETTER DESIGNS, HOWEVER I HAD THE PARTS ON HAND FOR THIS ONE, AND THERE'S REALLY NOTHING WRONG WITH IT.

THE SCHEMATIC BUILT AS SHOWN HAS 12V AC, 12V DC, HV AC, AND HV DC OUTPUTS.  THE HV VOLTAGE VARIES BASED ON FLYBACK, HOWEVER IT WILL BE IN THE 10KV RANGE.

MATERIALS        

FROM RADIOSHACK:
-12V 3A TRANSFORMER
-BRIDGE RECTIFIER
-LARGE 35V ELECTROLYTIC CAP
-TWO 2N3055 TRANSISTORS
-22 OHM 2WATT (WIREWOUND) RESISTOR
-220 OHM 1/2 WATT RESISTOR
-MISC SWITCHES AND BANANA TERMINALS
-ENCLOSURE

OTHER:
-FLYBACK TRANSFORMER

EQUIPMENT        

-SOLDERING IRON
-DRILL

PROCEDURE

WHY?

1.   BUILD THIS SCHEMATIC.  PUT IT IN A NICE BOX.

JUST DO IT.

SCHEMATICS

NOTE: THE HV TRANSFORMER SHOWN IS A TELEVISION FLYBACK.  THE SECONDARY HV WINDING SHOULD BE LEFT INTACT, BUT THE PRIMARY WINDINGS PICTURES SHOULD BE WOUND BY HAND.  MORE INFORMATION ON FLYBACK DRIVERS ABOUNDS ON THE WEB.

ALSO NOTE THAT THE DRIVER TRANSISTORS GET HOT.  THEY SHOULD BE MOUNTED ON A HEAT SINK, OR OUTSIDE THE ENCLOSURE AT THE VERY LEAST.  I RECOMMEND A 50/50 MIX OF THERMAL COMPOUND AND EPOXY SINCE THE TRANSISTORS CAN BE TRICKY TO MOUNT.

KNOWN PROBLEMS

THIS ISN'T THE GREATEST BENCH HV SUPPLY OUT THERE.  THE TRANSISTORS GET VERY HOT VERY QUICKLY.  NEWER TRANSISTORS WILL FIX THIS.  ALSO, THE DIODE STRING GETS VERY HOT, AND CAN MELT IT'S OWN SOLDER IF YOU'RE NOT CAREFUL.  A SINGLE HV DIODE WOULD SOLVE THIS PROBLEM. 

RESULTS


 

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