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W=(I^2)R so it needs to be rated at 0.33 times the maximum load current squared.
The resistor is there to create a voltage drop at the 'set' pin as load current flows so it adjusts the voltage to maintain a constant current.
I would anticipate some drift problems using opto-couplers like that, as everything is ground referenced you could directly couple the voltages from the potentiometers to the ICs.
There should be a ground on the regulator IC!
W=(I^2)R so it needs to be rated at 0.33 times the maximum load current squared.
The resistor is there to create a voltage drop at the 'set' pin as load current flows so it adjusts the voltage to maintain a constant current.
I would anticipate some drift problems using opto-couplers like that, as everything is ground referenced you could directly couple the voltages from the potentiometers to the ICs.
There should be a ground on the regulator IC!
Sorry, I missed that the current hadn't been squared in post #4 but as wwfeldman points out, 5W is adequate anyway. It is the temperature coefficient that really matters as it changes the current limit.
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