New Idea for an awesome atx shutdown

**moahdib** · 07-27-2001, 05:00 PM

Can someone tell me how to modify the Delay Power Off circuit found here: http://www.astron.nl/~smirnov/poweroff.html
so i can do the following:

1- monitor the Vacc or Remote On. (12V)
2- if acc line is off, it waits 10 min or so then connects the momentary power switch button (atx only) for only 2 sec giving signal to turn off.
Wait another 2 min to allow computer to do the shutdown before disconnecting the battery 12V source

3- if the acc line comes back on, within the 10 min, nothing happens =)
4- also has another switch in the dash to reboot if it crashes.

this would be a very simple automatic shutdown system for atx PSU's

You just have to set WinMe to either hibernate shutdown or standby.

com'on electronic guru's (arby, jeff, aaron ....)! what you guys think??

**jshrieve** · 07-27-2001, 05:18 PM

A week or two I had a discussion with Jeff about a circuit like this. He worked out some preliminary designs, but as you know he's been busy and when he has time he's mostly focusing on the DC-DC ATX PS. But I'm hoping when he gets some time he'll come up with something cool.

Already discussed/worked out a lot of the details..
But it'd be nice to divide the load a bit, or at least have a published circuit that does that, so people who wanna build it themselves can, even if none of the circuit gurus have time to build them.

**zootjeff** · 07-27-2001, 08:49 PM

Since there is so much interest, here is the circuit I designed with jshrieve's specs in mind. It can be made with a hand full of parts on a radio shack prototype board. You could probably get all the parts at radioshack too.

There is an RC network for every delay element. You need to determine the ammount of time you want to determine the R and C values. First figure out how much time you want each delay to be, then choose R between 5k and 5Meg. You will probably want to use a variable resistor (pot) for the ones you want to have variable. Then Choose a corrisponding C. Play with values of R and C until you find something that works, find values that make sence. (don't choose 1k and 1 farad to get 1000 seconds...)
T=RC so for 500ms, Say choose 1 uF for C, now we can go .5/1e-6 = 500k for R.

If you choose 1 meg and 500 uf you get 8 minutes etc..

Power Delay circuit Picture

I scanned this in with 4 shades of gray. It is about 120k (bytes not ohms.. :-) You would be better off trying to print it out or using photoshop if you want to understand it. It is just a first draft so don't expect too much.

Jeff_

**moahdib** · 07-28-2001, 05:51 AM

jshrieve what were your specs for the diagram? I can see that it also supplies 5V...is that for a character LCD of some sort?

**Tony S** · 07-28-2001, 07:07 AM

Moahdib, has anyone here got that circuit you first posted to work, besides the author? I tried building it thrice, the third time with every component new and every attempt didn't work. I'm sure it will work for someone, but for whatever reason it didn't work for me. I was using the 30A automotive relay Radio Shack sells and all NTE quality parts.

**moahdib** · 07-28-2001, 08:06 AM

I was just about to go buy the parts and make one but after seeing Jeff's new circuit I'm gonna hold off... you might wanna ask other people if they got it working. If you read on the webpage he says that the Drain (D) and the Source(S) are switched on the diagram, maybe that's the error you made?

**Tony S** · 07-28-2001, 02:37 PM

No, I remembered and marked my printout of the circuit with the S&D switched. I've built many a circuit before, many more complex than this, but I have to admit actually -figuring out/making- a complex circuit isn't my specialty yet. I've looked at this circuit a dozen times and I can't see why it wouldn't work, but yet it didn't for me. I even switched around the leads to the relay and it still didn't work. For the time being instead of a shutdown circuit I simply installed a SPST switch on an ignition-sensed wire off my interior fusebox. This way, if I know I'm popping into a store just around the block I can switch off the circuit instead of needless powering on/off the psu. The less switching on/off the better for the psu. Still, if I do get a good shutdown timer I'll try making it.

[ 07-28-2001: Message edited by: Tony S ]

**jshrieve** · 07-28-2001, 05:51 PM

moahdib,

I'm not sure. I gave a couple different plans for how the circuit would work to Jeff, depending on whether he just wanted to make a minimal circuit, or make a full featured one everyone can use..

And I'm not skilled enough to read what this one does. =)

**zootjeff** · 07-29-2001, 04:43 PM

Originally posted by jshrieve:
<STRONG>
And I'm not skilled enough to read what this one does. =)</STRONG>

This circuit will connect the power on to the PS as soon as the ignition goes on. If the ignition goes off, it will send an atx pulse 10 minutes (or whatever) then it will wait another 3 minutes (or whatever) then it will kill the power. If the power comes on before the atx pulse is sent, it doesn't do anything. If you hit the kill switch, it sends the atx pulse right away. If you hit the start switch, it will just send an atx pulse.

Jeff_