I'm trying to create a circuit to sense when an ac current rises above approximately 500 milliamp and have a load switched on. Should be very simple I would think except I have no experience with these sensors. I assume the sensor will provide a current which will need to be converted to a voltage and I could use the voltage to bias a mosfet. So the current would probably need to be converted to DC and there may need to be some kind of amplification and something to limit the voltage if the current is too high. Are there any circuit diagrams that show this with how to calculate values of components needed?

 

Check out the Honeywell sensors.
https://sensing.honeywell.com/sensors/current-sensors
The CSDA range may do it.
Max.

 

Thanks for the help.

 

Your description resembles antique analog design. There are Hall Effect sensors now which make all that obsolete.
I think Max just pointed to some.

 

A phototransistor glued to the led, or a optoisolator instead should work to trigger a circuit/relay :

----> http://www.clrwtr.com/Images/NK-Technologies/NK-AMPFlasher-Current-Indicators.jpg

 

Your description resembles antique analog design. There are Hall Effect sensors now which make all that obsolete.
I think Max just pointed to some.

Yes - I have a couple coming to test. The load is rated at 400ma and components say 250ma to 1a. I don't know if this means it is adjustable in some way or there is that much slack in the spec.

 

Another option you could consider is using an Amploc Sensor.

 

Another option you could consider is using an Amploc Sensor.

I started looking at this style until I was shown the digital ones that would work with such low currents. Made it very simple in that I didn't have to create an amplifier circuit. If the digital ones don't work and I can't find a digital with lower rating I will have to go back to these. Thanks.