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1N4148 and 10R resistor in parallel, any way to test diode?
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Chris Wilson:
I was wanting to check some out of circuit diodes, but they are each paralleled with a 10 ohm resistor. Is there any fairly straightforward way to test if the diode is fine without splitting it from the 10R resistor? And to check the 10R hasn't shifted much? Thanks
capt bullshot:
You can check the 10R resistor using a common Ohmmeter, I suppose it'll apply a rather low current (like 1mA to 10mA). So the voltage across the resistor stays well below the diode forward voltage.
For testing the diode, you could apply a constant current of 100mA that would cause 1V drop across the resistor. With diode in parallel, the voltage drop will be lower, approximately the diode forward voltage at 60mA ... 70mA (0.6V ... 0.7V).
Brumby:
.... and the reverse voltage will be 1.0 V
The 1N4148 is a signal diode, not a power one, so it's important to keep the current down. 100mA is ideal.
spec:
--- Quote from: capt bullshot on December 15, 2018, 09:39:10 pm ---You can check the 10R resistor using a common Ohmmeter, I suppose it'll apply a rather low current (like 1mA to 10mA). So the voltage across the resistor stays well below the diode forward voltage.
For testing the diode, you could apply a constant current of 100mA that would cause 1V drop across the resistor. With diode in parallel, the voltage drop will be lower, approximately the diode forward voltage at 60mA ... 70mA (0.6V ... 0.7V).
--- End quote ---
C L E V E R :)
Chris Wilson:
That works fine and will save me a lot of time, many thanks :)
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