ADWSystems
Member
To make a long story short and to keep it simple, I need to detect when line voltage is present and then supply a logic or open collector output as the input to a downstream circuit.
My thoughts were to use a PS2565 back-to-back diode input optoisolator with Vf=1 and If=80mA. Since AC line voltage is 170 peak (120Vrms), I need to drop 169VAC without generating a TON of heat (ie., not using a resistor). My thoughts, use a 250V capacitor. I did this in a design once about ten years ago but don't remember all the design techniques that go along with it. If I want to drop 169V at 50mA I need a 3380 ohm impedance. So far so good.
If I remember correctly the impedance of capacitor is 1/(2pi*f*C), or capactance = 1/(2pi*f* impedance). With impedance=3380ohms and f=60Hz, I get a 1.25uF capacitor. How am I doing to far?
So will this work or am I going to electrocute myself or burn the house down?
My thoughts were to use a PS2565 back-to-back diode input optoisolator with Vf=1 and If=80mA. Since AC line voltage is 170 peak (120Vrms), I need to drop 169VAC without generating a TON of heat (ie., not using a resistor). My thoughts, use a 250V capacitor. I did this in a design once about ten years ago but don't remember all the design techniques that go along with it. If I want to drop 169V at 50mA I need a 3380 ohm impedance. So far so good.
If I remember correctly the impedance of capacitor is 1/(2pi*f*C), or capactance = 1/(2pi*f* impedance). With impedance=3380ohms and f=60Hz, I get a 1.25uF capacitor. How am I doing to far?
So will this work or am I going to electrocute myself or burn the house down?