Does anyone know where I can obtain design details to enable me to build my own battery powered NPN/PNP proximity switch tester ?
woodglass...
Proximity Switch Tester - Design Required
Jul 01, 2006
3 Replies
Take a battery and connect to a series connected resistor and red LED to switch output terminal. Continue from switch output terminal through series connected resistor and green LED to switch common terminal and battery negative.
If you have an NPN type switch, the output is in one of two states:
1)Active, pulled to common - in which case red will light and green will not.2)Inactive, floating - in which case both LEDs will be lit.
If you have a PNP type switch, the output will be in one of two states:
1)Active, pulled to switch supply - in which case the green will light and the red not.2)Inactive, floating - in which case both LEDs will be lit..
He will need to run 3 wires to the switch... +, -, and output. Also, some prox switches need 12VDC minimum to operate. He probably can get away with a
9V battery, but two in series will be better.Ben Miller
eej
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