"klem kedidelhopper" wrote in message
...

On Jul 22, 2:38 pm, mike wrote:
On 7/22/2012 10:02 AM, wrote:



I also have two adjustable current power supplies like you mentioned.
So in other words, what you're saying is reverse bias the diode across
the supply, (cathode to positive) and look for leakage as read on the
current meter? Lenny
Correct, with precaution of using a current limiting supply or
increasing the voltage slowly.

PlainBill

Beware using current limited supplies to test stuff, especially junctions.
You can set the current to zero, but the energy stored in the
output capacitor can zap the device. Suggest using an additional
scheck zen

When checking zener diodes I usually put a series resistance of about
1000 ohms in series with the unknown diode. Then I increase the supply
voltage slowly until the diode clamps. Then I know the zener voltage.


###My homebrew zener measurerer is a little risky but works a treat.

### Its a pair of reservoir electrolytics from scrap monitors in series,
with the tap to one AC leg of the bridge rectifier to make a voltage
doubling rectifier, AC current is limited by a series pair of 68k/2W
resistors (were the startup resistors for the UC3842 in a monitor PSU).

### In parallel with the test clips & sockets for the DMM probes is a
shorting switch in series with an inrush limit NTC thermistor to dump any
charge on the caps before connecting D.U.T.

###So far, after quite a few years use - only one D.U.T. has acted as a
one-shot relaxation oscillator. Its satisfactory for checking the PIV of
1N4148 type diodes including similar size Jap types with unknown colour band
coding.

###On the UK 230VRMS supply, the doubler/rectifier means I can check PIV
upto about 600V - that's probably limited by leakage on the bridge rectifier
I pressed into service.