It is my fault that I did not record of the defective optocouples.
Cheers
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It is my fault that I did not record of the defective optocouples.
Cheers
Would you be so kind to provide schematics which is suitable to test both of the failure states you mentioned of an optocoupler?
Thank you.
No big deal, hegefer:
-Just hook the (normally open) push-button between the opto-couplers Pin 2 to ground (instead of as per the schematic).
Then the +voltage will feed the opto-transistor at all times, or rather as long as the +supply is on,
but the button will draw current through the coupler's LED only when pushed.
Thus you check that:
1) The transistor won't lead when the internal LED is off (No push: External LED OFF),
2) That it'll lead when, and only when PB is pushed (Push and hold: LED lights up), and
3) That the transistor also shuts off when PB is released (Release PB: LED goes off,
thus eliminating that no stray, internal current keeps it ON,
an indeed very rare, but still possible fault mode)
2 cents
Dear DIYSwede,
Thank you for your quick and detailed answer.
hegefer
Circuit with ground switch:
It would be easier if it could be tested directly on PCB. :)