zener tester

[stj]

this is old, but very simple.
and it works.

i decided to share.

[SteveNielsen]

Re: zener tester

Cool. Could you use a multimeter set on 200mV range instead of the Maplin gw01b?

[selldoor]

Re: zener tester

Should probably be stickied in somewhere in the TV section or in the equipment section
if you want to ask a mod to move it

[SteveNielsen]

Re: zener tester

Equipment forum is probably most appropriate but it seem ok here to me too.

[stj]

Re: zener tester

Cool. Could you use a multimeter set on 200mV range instead of the Maplin gw01b?

not unless you want to blow it up.
you set your meter to 200v or higher.

i built one without the meter and connect it to my multimeter.

the circuit generates a ramping voltage that starts at 0 and rises to over 200v

[stj]

Re: zener tester

just to add, if you use your multimeter, you connect it across the zener

[SteveNielsen]

Re: zener tester

Sorry, I misread some stuff. Thanks for the info.

[budm]

Re: zener tester

If you already have variable output DC power supply, than all you need is the resistor to limit the current through D.U.T. and the meter hooked up across the D.U.T.
Or build this portable tester.

[stj]

Re: zener tester

shall i draw a modern schematic of a variant that uses a multimeter and a more common transformer?

[SeanB]

Re: zener tester

I built one years ago using a small surplus 60VAC transformer and a 10mA constant current source. Was quite useful to test zener diodes or to use as a simple 10mA current source. I built it to handle a 80V zener that we used that would fail every so often, but it was also useful to test high voltage rectifier diodes that had a 20V or so forward voltage drop. Reverse voltage testing on those was with a 10kV insulation tester, which would show any gross faults, but which was not much use as the equipment in question ran at 30kV on the anode. At least the 10kV allowed us to trouble shoot without burning up anything else in the test phase. It was way to high for any other use, as it would happily kill any mains rated cabling it was attached to, and would make things like sockets arc over internally.

[Mr.Orange]

Re: zener tester

Built a simple one years ago for testing zeners from a blacklisted supplier, the only supplier (Arrow) that had that value. One of the production staff had to sit there all day testing zeners , felt sorry for them but they said is was relaxing. about a quarter were within tolerance. Anyway power supply a suitable watt resister (could just use a couple in parallel) and a bench meter does the job.