On Thu, 07 Sep 2006 08:35:30 +0100, VentureOverland
wrote:

On Tue, 05 Sep 2006 21:37:45 +0100, Colin Stamp
wrote:

On Tue, 05 Sep 2006 08:05:46 +0100, VentureOverland
wrote:



Colin,
Sounds like a timer of some description would be just the thing. A
circuit diagram woud be much appreciated.

Many Thanks.
Jon
Regards,

Jon
VentureOverland
http://www.ventureoverland.com


Here you go. It's quick and dirty, but hopefully, it'll do the job...

http://www.stamp.plus.com/temp/TimeDelay.JPG

The components are :-

Resistor - 390R 0.5W - Farnell 9340513
Capacitor - 6800uF, 16V - Farnell 8767203
Relay - 12V 2250R coil - Farnell 1175000

The delay should end up at about 2.5 seconds. The choice of relay is a
bit critical, I'm afraid, since it's such a simple circuit. The coil
resistance does need to be high or it won't pull in with the 390R
resistor.

Cheers,

Colin.

Colin,
Many thanks for this, its great... Is it possible to get the 2.5s
stretched out to about 5s as 2.5s is just a little too quick? I
reckon the "pop" from the pc is about 4s after switching on.


You could just add another 6800uF cap in parallel with the first,
which should work, but the values are starting to get a bit silly. It
might be worth going to a slightly more sophisticated circuit for
extra versatility. A quick Google found this:-

http://home.cogeco.ca/~rpaisley4/LM555.html#30

Try circuit #2, with :-

C1 = 100uf, 16V
R1A = 1K
R1B = 100K preset

That should give you a variable delay up to about 10ish seconds.

Cheers,

Colin.