ac current sensor

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r3richard

Joined Feb 22, 2011
3
I've made a simple coil to sense current flowing to the upper and lower elements of two hot water heaters of a hydronic heating system. An led with current limiting resister lets led show when a heater element is on so I can tell if the system is keeping up with the demand or not. But, the collapsing ac when heater turns off is frying my led after a few weeks. I need a bit of guidance to add a diode or choke or what?
 
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#12

Joined Nov 30, 2010
18,159
You're letting AC voltage get on the LEDs. Several cures. Add a diode rectifier in series with each LED. Add a diode rectifier in parallel with each LED. Put 2 LEDs in parallel, but backwards to each other.
 

chrisw1990

Joined Oct 22, 2011
551
that sounds a little too high to me?
if it is 3V across the led, maybe thats whats burning the leds in addition to any potential reverse voltages
 
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