Hola Y'all,
My question is there a quick test to check a zener diode to see if its good or bad?? I checked a new one and it measured open in one direction and several meg ohm in the other direction and the zener in question read ~75 ohm in both directions which I suspect is bad. Your comments are welcome.
Regards, Elwood
My question is there a quick test to check a zener diode to see if its good or bad?? I checked a new one and it measured open in one direction and several meg ohm in the other direction and the zener in question read ~75 ohm in both directions which I suspect is bad. Your comments are welcome.
Regards, Elwood
Most 'Zener' diodes are in practice several avalanche diodes in series - how many depends on the voltage rating.
So both the forward and reverse voltage drop may be larger than an ordinary digital avo-meter is designed to cope with.
Some old moving coil meters are better at this since they use a rather high voltage battery (some up to 15 or 22V)
So both the forward and reverse voltage drop may be larger than an ordinary digital avo-meter is designed to cope with.
Some old moving coil meters are better at this since they use a rather high voltage battery (some up to 15 or 22V)
Should read as a normal diode when forward biased... ie on the diode range on a DVM it will read 0.7 ish meaning 700 mv dropped. 'tother way about and it shouldn't read as general rule for anything over a couple of volts or more but that's useless for testing accurately.
All you need is a battery of higher voltage than the zener and a restor to limit the current. Choose resistor as follows (or even better use a FET as a constant current source)
R= (Vbatt-VZener)/0.010
and measure the voltage across the zener and see if it agrees with the device in question.
Oh yes 75 ohms each way... "Oh my" so it is faulty
All you need is a battery of higher voltage than the zener and a restor to limit the current. Choose resistor as follows (or even better use a FET as a constant current source)
R= (Vbatt-VZener)/0.010
and measure the voltage across the zener and see if it agrees with the device in question.
Oh yes 75 ohms each way... "Oh my" so it is faulty
Should read as a normal diode when forward biased... ie on the diode range on a DVM it will read 0.7 ish
Only some 'zeners'. Not if it is a compound device, which many are.
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