How many Amps does a monitor need? Laser Printer?

[Szech]

After I saw a schematic for hooking up a relay to turn on/off a water pump with the computer, I got the bright idea of doing the same with the rest of my peripherals. The relays that I found off of www.allelectronics.com (http://www.allelectronics.com) go up to 10 amps for a 115VAC relay. Is this enough for a energy sucker like a monitor and a laser printer? I will not be hooking them all up to the same relay. I might be dumb, but I'm not stupid.

[Graham]

Szech,
Monitors probably less than 2A, laser printers, a lot less (both at 115V).
One 10A relay would do a lot of peripherals, be careful though, the current drawn at switch on can be much greater than the running current. Some sort of spark quenching would be a good idea, small value capacitors across the relay contacts, be sure they have a working voltage greater than your supply.
I did do something similar, had my monitor turn off with the pc( no pass through connector) http://www.hollies.org/monitor.htm
used the 12v pc supply, coud use that to control all sorts.


Have a look see.

G

[This message has been edited by Graham (edited 04-25-2001).]

[samwichse]

If you make it and it works well, you should post exactly what you did here, because I was looking for the exact same thing, but all I got on asking around was that I should "buy a power strip with a switch on it."

[Szech]

Goodie Graham http://www.sysopt.com/forum/biggrin.gif! Just curious, if I got a few relays (three or four to be exact), and hooked them up separately to a surge protector, would that be sufficient precaution against the problem of first switching on? When you say put a capacitor across the relay contacts, which contacts are you referring to? The +12VDC and Ground? Or the two 115VAC source wires?

Thanks!!!

[Andy_L]

Laser printers draw a lot of power, for instance an HP 4000n draws 330 watts max, and it is recommended the supply circuit be rated at 8 amps at 110 volts.

[Graham]

Szech,
The capacitors go across the ac relay cantacts, L to L and N to N on the diagram,(the ones that actually switch the power), they are there to (help) prevent arcing, a surge protector would (help) remove these spikes from the line and getting to your kit, but not stop them occuring. So... you would need two per relay, assuming you switched both ac lines.
You could switch the power to a distribution board (multi socket) with one relay.

G