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Topic: Circuit board design - Monitoring Inputs using Red/Green LED for visual status (Read 213 times) previous topic - next topic

curttori

Hi all - many thanks in advance for your feedback/help!

I'm designing a circuit board to monitor multiple reed switches (NC) for doors & windows. Will ultimately use I2C with multiple MCP23017's monitoring 50+ Inputs; driving both IO Relays & a ZWave controller on a RasPI.

On the board I would like green LED's for Closed state & red LED's for Open state. I've accomplished this on a breadboard with a PNP transistor & pulldown resistor (see schematic). My question - is there a simpler design than what I've shown in the schematic??

Never mind the higher resistance values driving the LED's. I know I should go lower but keeping resistance a bit higher to help keep total current draw down.



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