PIC feedback

[Tafie]

I am doing my final year college project and am doing web based monitoring and control. In the setup, there is a PC web server accessible via intranet. THis web server connects serially (RS232) to a microcontroller (Microchip PIC16F874). The PIC micro controls a relay to switch on an ac circuit. I need somekind of SAFE feedback to report if current is flowing in the ac circuit after energising the relay. The micro sinks up to 25mA at 5V DC. I am considering connecting a transformer to couple the high current ac from the stepped down voltage but am not sure how to do it if at all possible. Any help is appreciated and any other suggestions and modifications to my idea are very much welcome.

 

[Mr RB]

Google for "ac mains optocoupler" that should get you on the right track.

 

[kchriste]

You could also use a current transformer for that. Something like this could be easily adapted to trigger your PIC. Or this which is even easier, but a little more expensive.