Flyback HV Return and HV rectifiers

High voltage rectifiers drop more voltage than the diode checker or ohmmeter on multimeters test at. On mine the test voltage is less than three volts. By using a higher voltage (18 volts should be plenty) and a voltmeter, the barrier voltage will be overcome and it will be possible to check an HV rectifier. The voltmeter has a very high internal resistance so the test current will be very small.

For a DC flyback:
The anode is connected to the voltmeter (+) lead.
The voltmeter (-) lead is connected to the battery (-) lead.
Using the battery (+) lead, probe the flyback pins until you get a voltage reading. The value will be the battery voltage minus the rectifier voltage drop.

Category:

Science & Technology

Tags:

• DC
• flyback
• HV
• return
• rectifier
• diode
• check

[npaltmp]

Good tip. Never seen or read of anyone using it before. I knew this trick would probably work; I just never tried it. Your video did however provoke me to recreate your setup to test the resistance of the secondary. I switched the MM to dc amps mode and got a reading of 0.12 mA. So 11.75 V / 0.00012 A = 97916.67 kOhms =~ 98 kOhms. Wow! That almost doesn't seem right.

[helixwinder]

@npaltmp It's not that simple. The diode has a constant voltage drop and the winding drop varies with current (applied voltage).This test is only to determine continuity not resistance. The diode is dropping most of your 11.75 volts, and exactly how much is hard to know since you will get a different reading depending on the current through the winding and diode. Maybe if you measure the drops at different voltages you can determine what can be attributed to the winding alone? Good luck.

[Alex1M6]

@npaltmp Same with me, I basically jumped right in to the high voltage stuff and drawing arcs from HV transformers. Now I am taking a break from high voltage and concentrating on learning a lot of the basics that I originally skipped. I mean I know ohm's law an all that good stuff but there is quite a bit I don't know.

[npaltmp]

@helixwinder Yeah, that actually makes sense to me now; I just didn't think it through. Electronics has been just a hobby for me and I've always been a bit too eager to jump to the fun stuff. HV, microcontrollers, etc. Only recently have I been getting more serious about it so it is getting to be time that I go back and study the basics.