I am trying to find a circuit to replace a relay with a 120VAC coil. The relay was used to sink a DC signal to ground. I need to find a solid state circuit to replace the relay, with a cost limit of around $10- $15 US. Here's the catch: the AC line must be isolated from the DC, and it must be reversable, in case the outlet is wired wrong. I have gone over and over this, but the only circuits I can come up with will always turn on and stay on when the AC line is reversed. I was thinking of using a mosfet to sink the DC, but you can't isolate the supply, or there is no reference for the mosfet gate-source voltage! This is like a dog chasing it's tail. I thought it was an interesting problem. Maybe someone here can come up with something. Right now, I am thinking of finding a very small PC mount tranformer to supply an isolated AC signal (doesn't need to source any current- just need the voltage).
Steve
Steve
Yes, but I don't want to have to re-design a pcb in a few years because an opto went obsolete. I guess I forgot to mention that it should use easily replaceable parts.
I will probably stick with the relay, because it's cheap and easy (and this is for work).
Good suggestion.
I will probably stick with the relay, because it's cheap and easy (and this is for work).
Good suggestion.
There are almost always lots of good deals to be had on used Solid State Relays.
http://www.mpja.com/productview.asp?product=12808+RL
OOPS thats backwards from your application...
http://www.mpja.com/productview.asp?product=12808+RL
OOPS thats backwards from your application...
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Perhaps a little closer:
How much current did you need to sink?
Will this work:
http://www.mpja.com/productview.asp?product=14578+RL
This one might be a little closer:
http://www.mpja.com/productview.asp?product=7936+RL
How much current did you need to sink?
Will this work:
http://www.mpja.com/productview.asp?product=14578+RL
This one might be a little closer:
http://www.mpja.com/productview.asp?product=7936+RL
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