Electronics PC Relay Q's

linear or anyone else for that matter,
I have noticed on my pc relay board kit


that when the computer starts up, the relay randomly turns on each relay on/off a few times before windows loads up (in DOS) and then when windows loads up, all the relays are turned on. Can i provent this from happening? I dont want the relays to be on until i turn them on myself. Is there a relay that i can use to delay the 12v current going to the board until windows has loaded up?

Thanks,
David

 

That's the parallel port being tested.

Is that the power input socket on the RHS? What happens if you don't switch the board power on until after the boot sequence has finished?

 

When no power is turned on on boot up then applyed to it when windows is finished loading, the relay board turns on (all relays) like if it was hooked up at start up. Only difference is that it doesnt go crazy in DOS startup of the computer. Thats what i dont want. I just need something that delays the current to the board for about 2 mins or less as the computer boots up because i dont want to have to turn the board on every time....


David

 

This could be adapted to do that.
http://www.bit-tech.net/article/70/

 

i didnt see in that artical how long a delay was for it? Do you know how long it takes to turn on?

David

 

It depends on the resistor and capacitor used.

 

so what would i need to buy to have a delay of like 2-3 mins after startup?

David

 

There's a couple on this page to drive a relay, the 555 one is perhaps easiest and will easily do a few minutes.

Formulas to get time are on the page. Use a low-leakage tantalum cap in any design. Rather than use the switch to start the delay, you'd connect the power to a molex.