Relay for signals

Hello everyone! I just was wondering, how I can use a relay for switching a signal. What I came up with is something like that: Basicly my problem about it is, that as soon as I use an alternating signal as an input for the relay, the relay remains closed even if I ground both sides of the coil. I would be glad, if you could point out, what I am doing wrong, since I am new to CL.

Thank you a lot!

by kerwindena
December 01, 2013

The relay is working fine.

What is confusing you is that the relay has a very large but finite open circuit resistance of about 1e15 Ohms.

This is 1000 times smaller than the load resistance presented by R2 at 1e18 Ohms so you see little visible difference between V(out) with therelay open or closed.

Reduce R2 to << 1e15 Ohms (try 1k!) and everything looks fine.

Here's a demonstration of the open circuit resistance of CL relays:

Note that the same sort of comments apply to the voltage and time controlled switches (though I'm not certain of the fixed switches) and the DC leakage resistance of capacitors in CL.

by signality
December 02, 2013

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