Need Help: 12V Timed delayed Auto on/off switch

**jhowle** · 11-05-2009, 08:39 PM

Hello, i need some help. Sometimes when i turn my car pc on the screen turns on faster than the PC and the screen stays in standby because it doesnt since video signal.

The M2-ATX power supply has a user adjustable time delayed on off switch that starts counting once a 12v ignition signal is recieved. This is what i want to have happen when i turn on the PC. I want to delay power for the screen for approximately 3 sec since it just turns on when i gets power and hopefully it will stop staying in standby. Any help here is always greatly appretiated.

**durwood** · 11-06-2009, 01:31 PM

Use the 12V from your m2-atx to power or turn on the screen. If you can't spare current from your 12V line, use it instead to tigger a relay which supplies 12v from the car.

What screen doesn't have auto sense?

**jhowle** · 11-07-2009, 01:28 PM

it does have autosince but for some reason does this. I built a little box consisting of a relay and some switchs to give power to the computer. Basically i have momentary push button to start the relay and the relay stays closed after you relaease the button but only opens when you shut off the car. I wish to inside this box a smal circuit that basically does what i described and also rectifies the current to 12v.

**Curiosity** · 11-07-2009, 07:05 PM

USB has quite a long delay. You could add a 5V relay off USB to trigger your latch. It might be half way into the boot, but would do the trick.

**jhowle** · 11-08-2009, 03:37 PM

i guess that culd work but still i just wanna build something inline

**justchat_1** · 11-08-2009, 05:04 PM

Originally Posted by Curiosity

USB has quite a long delay. You could add a 5V relay off USB to trigger your latch. It might be half way into the boot, but would do the trick.

Alot of motherboards will power on usb for a second or two as part of a self test when the system first boots and then cut power till the OS gains control. Better off just using the 12 or 5v line of the PSU.

**Curiosity** · 11-08-2009, 05:47 PM

That's true. It will power up to check for bootable devices, but can be disabled. I also sell timers for this kind of thing.

The M2-ATX should work for the supply though. Why aren't you using that? Search ebay for AX3022 and you'll see what I'm using for mine right now. It has a very clean output and it's cheap. I have it set for 12.1V and it has never cut out and always stays cool.

**jhowle** · 11-09-2009, 11:57 PM

do you know of anything i can build myself?

**Curiosity** · 11-10-2009, 12:43 AM

Sure. There are lots of on delay circuits. 4th one down here http://www.bowdenshobbycircuits.info/page2.htm
That was from an off delay thread a few days ago. I forget what it was for.