Vac > computer input

[trend]

Hello, I am looking for a way for my computer to tell if there is 0vac or more than 0vac (will be a split second 27vac)voltage going through a line, any ideas? ( The only idea I have is some sort of relay, but i cannot find a relay that does vac)


thanks for any help_Lee

 

[f95toli]

Why not use a voltage divider and line-in on the soundcard?
But be carefull, or you will fry your soundcard.

 

[Geniere]

As f95toli stated plus I'd probably couple it with a capacitor.

 

[FrankSchwab]

Well, another simple way....

RS-232 is specified as using up to a +/- 15 volt swing IIRC. If you put a voltage divider inline with, for example, the RI (or DCD, or DSR) handshake lines on the RS-232 port, you can open the port and get a callback on a change of state for that pin. That's about 5 lines of code, and very little hardware.


Might work, might blow up your serial port. You decide.

/frank