Quote Originally Posted by igeorge View Post
Hello,
I have a line where the current varies from 1 to 5 amps.
I would like to insert a resistor which will turn on an optocoupler rated at 1.5 volts , 10 mA
The issue here is that at 5 amps i need a 0.24ohms resistor , and at 1 amp i need a 1.2 ohm resistor.
Assuming that i use the 1.2 ohms resistor, at 5 amps will generate 6 volts and fry my opto.
I need help to solve this issue, which i do not know how to do it
Regards
Ion
iF you place a 450R resistor in series with the opto, that'll ensure the voltage doesn't exceed 1.5V/10mA at the opto for 5A through the element ....of course the opto will only then 'get' 300mV if the element current drops to 1A....but without knowing more about the opto blah blah