Power Supply Sequencing

[phildo77]

Hey all,

I'm pretty far along on my 4-player "Game Grid" machine.  One of the issues I'm thinking over is the power on sequencing.  I'm using a newer ATX computer (momentary switch on) and an older DAEWOO TV that also has a momentary activation switch.  Because of the momentary action of the TV and PC I'm forced to connect an external momentary switch to both.  So turning on the box consists of:
1)  Flip main power switch (Which I would like to turn on everything)
2)  Press momentary switch to turn on TV
3)  Press momentary switch to turn on PC.

I've been thinking that I could program a PIC or some simple ROM to sequence a couple of relays on main switch power up.  Anyone played with this stuff?  What does everyone generally do for power on sequencing?

[phildo77]

Whoops... I just saw the FAQ on this.  But I'm still curious on how other people have done this if anyone has come up with any more clever solutions.

[phildo77]

Can anyone tell me why this wouldn't work?

Note:  the ATX supply always has 110V connected.

Heres the basic circuit.  When Main power is off the NO relay is open and the NC is closed (naturally).

When the mains are switched on, the AT supply automatically turns on (AT supplies are hard switched).  This closes the NO relay and completes the ATX  supply motherboard toggle which turns on the ATX supply.  Once the ATX supply comes up the 5V from the ATX supply opens the NC relay removing continuity from the ATX supply toggle.  So this creates a pulse or momentary connection causing the Main PC supply to turn on.

edit:  The labels for the toggle nodes are in correct, they should read "ATX".  Not "AT"


ANyone see why this won't work?

[ShinAce]

I would test the momentary switch to see if it interrupts a current, or switches a digital signal.

Then I would make it so that after the main power is turned on, there might be a small delay(1 second), and then the 2 momentary buttons would be held down using a relay, IC, or what have you.

To turn a monitor or computer on, you simply need to press the button. To turn it off however, you need to press AND release the button.

[phildo77]

To turn a monitor or computer on, you simply need to press the button. To turn it off however, you need to press AND release the button.

Actually if you hold the POWER button on (keep the power switch pressed in) on an ATX MB the power will turn on then turn off a couple of seconds later.  So the contact needs to be removed once the ATX supply comes up.  At least thats the way it is with my MB.

But I believe that the TV will stay on if the contact stays connected.