I am working on a little xbee project where I detect a door bell, which is 18vac ( I expect this can vary from 15vac to 24vac). I'm a software guy and have made smoke when I fiddle with hardware so I thought I'd ask for some advice.
the current plan is to use a H11AA4M which is a AC Optoisolator simular to a 4N35 but with two LED's.
What I *think* I need to do is simply have a resistor in series with the LED side to limit the current.
My calculations are :
18V - 1.2V = 16.8V voltage from transformer minus voltage required by Optoisolator
16.8v / .010 = 1680 ohm voltage to be dissipated divided by current (10ma)
So will a 1.8k ohm resistor in series work with no smoke?
also could I do the same thing with a cheaper 4n35 and a 1n4001 diode?
Any other solutions to the problem?
the current plan is to use a H11AA4M which is a AC Optoisolator simular to a 4N35 but with two LED's.
What I *think* I need to do is simply have a resistor in series with the LED side to limit the current.
My calculations are :
18V - 1.2V = 16.8V voltage from transformer minus voltage required by Optoisolator
16.8v / .010 = 1680 ohm voltage to be dissipated divided by current (10ma)
So will a 1.8k ohm resistor in series work with no smoke?
also could I do the same thing with a cheaper 4n35 and a 1n4001 diode?
Any other solutions to the problem?