can anyone design a pulse circuit......

Jamez_Warner · 12-01-2003, 03:09 PM

can anyone think of a circuit that will - when receiving 12v, switch a transistor on for about a second and then switch off ? ( can this be done simply with a capacitor or something? )
James

SuperSonic · 12-01-2003, 03:38 PM

This should serve you right.

I made it myself too it is fully functional and a breeze do make. Not my design!

Jamez_Warner · 12-01-2003, 03:46 PM

thanks, but I allready have a shutdown controller, i just want a circuit that when powered up with 12v closes a transistor for about a second then off again - according to the simulator the below image will work - but I would have thought it could be done simpler with a few caps and resistors?
James

zootjeff · 12-01-2003, 04:29 PM

Quote: Originally Posted by Jamez_Warner

thanks, but I allready have a shutdown controller, i just want a circuit that when powered up with 12v closes a transistor for about a second then off again - according to the simulator the below image will work - but I would have thought it could be done simpler with a few caps and resistors?
James

Just put the 10uf cap in the holes. round is minus and square is plus.

-Jeff

Jamez_Warner · 12-01-2003, 04:36 PM

i have ( works ), but of course we have hit the problem of it malfunctioning when I turn computer back on before timer has expired

James

beakmyn · 12-01-2003, 04:51 PM

This site should get you going.

http://www.the12volt.com/relays/page5.asp

Ricky327 · 12-01-2003, 05:24 PM

This site should get you going.

http://www.the12volt.com/relays/page5.asp

Wow...didnt know someone can even think of using 5 relays just to do something very simple. He must have lots of spare relays.

Its an interesting page though

Jamez_Warner · 12-01-2003, 05:28 PM

thanks ricky that's perfect - I have formed the following diagram:

this means with jeff's shutdown controller - it will give a power on pulse everytime the pc recieves power so you can't lose sync by turning key again while the timer to shutdown is still counting... ( ppl with jeff's controller will understand )

Ricky327 · 12-01-2003, 05:30 PM

Jamez_Warner

I think you supposed to thanks someone else

Jamez_Warner · 12-01-2003, 06:22 PM

lol

Ricky327 · 12-01-2003, 06:25 PM

Yup the guy called beakmyn who posted the link

rgardjr · 12-01-2003, 07:02 PM

I bought one of these cheap off ebay DEI 528T Pulse Timer:
http://cgi.ebay.com/ws/eBayISAPI.dll...ory=14934&rd=1
Adjustable pulse length. I paid $9.90 with shipping.

none · 12-02-2003, 12:07 AM

Jamez,

I made a circuit almost identical to yours (except with a diode, similar to Mike Carr's design,) and it has a problem with the cap discharging and sending a second pulse a minute or two later. Let me know if yours works. I even spoke to Mike Carr about it and he admitted that he had no idea, he just copied the circuit from someone else himself.

What is the blue thing above the resistor in your design?

SuperSonic,

Your controller doesn't send a second pulse and shut down the computer a minute or two after starting? Do you mind if I ask the exact specs of the parts you used? My circuit is only half that design since I only need the startup pulse, but I think it should work anyway.

Thanks.

.

Jamez_Warner · 12-02-2003, 06:23 AM

its just a tes probe ( its a screenshot from a circuit simulator)

none · 12-02-2003, 11:36 PM

BTW I'm now building a circuit based on a 555 chip.

.