Relay for water cool system

[Bongo]

I need some ideas for how to switch a 110 source with a 12 or 5 volt from a pc. Something that will turn on the 110 when the pc is powered up. Also which leg of the 110 would be best to switch? And how many amps would the relay need to be in order to handle about 20 watts worth of appliancses? thanks in advance for any help you guys can give....

[russlk]

Your PC no doubt has some spare connectors for powering periferals which are either 12 or 5 volts. You should switch the hot side of the 110 volts, otherwise the load will be "hot" even when the switch is open which could be a shocking discovery. A 1 amp relay will handle 100 watts. If the load is inductive, put an R-C snubber across the contacts to reduce arcing.

[Externet]

Or, use the monitor outlet if you have one.
Miguel

[MrAl]

Hello,<p>You will have to first build or purchase an
i/o card. You can use the i/o card to drive
a relay. There is a device called a
'solid state relay' that is really a triac
driven by an opto isolator. This would
work out very well most likely.
If you want to use one of the ports, you will
have to build or buy an i/o card that works
with one of the ports. With the serial port
this probably wouldnt take too much.<p>20 watts of power doesnt sound like much,
are you sure it's not higher then that?<p>Good luck with your circuits,
Al

[bobsRAC]

You could build a board with a microController to PWM some SCRs. This would allow the board to vary the power without dissipating a plethora of heat.