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Topic: 48 V signal though opto isolator into Arduino (Read 1 time) previous topic - next topic

stealthtransam

I'm trying to take some -48V signals into an Arduino.  Using a voltage divider circuit i'm dissipating about 3 watts of power.  Anyone know of a better way to feed 48 V into an optoisolator?

mowcius

Quote
Using a voltage divider circuit i'm dissipating about 3 watts of power

Use much larger value resistors in your voltage divider circuit...

But as Richard says, surely a current limiting resistor would suffice?

Mowcius

stealthtransam

a current limiting resistor is causing too much heat =(  I need at least 40ma though the circuit to kick on the opto.  I'll post a schematic in a bit.

Professor Chaos

#3
Oct 01, 2010, 10:44 pm Last Edit: Oct 01, 2010, 10:50 pm by lefstin Reason: 1
Darlington optocoupler?

stealthtransam

here is the circuit.  as you can see I have an input voltage of -48VDC and i'm trying to have that send a high signal to the arudino when the 48 V signal is lost.  the problem is for a circuit that will be in the ON state for most it's life .7Watts of heat across R1 is just too high.


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