Timer circuit advice

divine` · 24 Jul 2007 at 20:46

BenST said:
I don't know of any simulation software unfortunately.

http://www.crocodile-clips.com/crocodile/technology/

Hope that helps

BenST · 24 Jul 2007 at 20:51

Cheers fella

Burnsy2023 · 30 Jul 2007 at 22:57

Probably a bit late but here goes anyway:

Don't forget to decouple the power rails with a decent size electrolytic capacitor and a 2uF polyester capacitor in parallel.

Burnsy

Adam_151 · 31 Jul 2007 at 00:14

Something like this should do the trick

In the real world I'd probably find it quicker to use a microcontroller though

sniffy · 31 Jul 2007 at 00:26

Out of interest, which software did you use to create that?

THMRK · 31 Jul 2007 at 00:27

I really wanted to make a "flux capacitor". But It'd be redundant now.

Adam_151 · 31 Jul 2007 at 00:35

sniffy said:
Out of interest, which software did you use to create that?

That was done in crocodile clips 3

sniffy · 31 Jul 2007 at 00:43

Adam_151 said:
That was done in crocodile clips 3

Thanks

Nomisf · 31 Jul 2007 at 00:49

Dont know if we are there yet, but maybe ...

555 Mono (for delay ) -> While on for 1-5 seconds is also charging a cap/variable resistor based potential divide, which when state changes affects the enable/trigger (cant remember) of the chip.

God knows im tired, will think in the morning

divine` · 31 Jul 2007 at 00:52

sniffy said:
Thanks

The newest version is now called Crocodile Technology and I linked to it above

sniffy · 31 Jul 2007 at 01:04

divine_madness said:
The newest version is now called Crocodile Technology and I linked to it above

Nice one, cheers

Burnsy2023 · 31 Jul 2007 at 14:00

Adam_151 said:
Something like this should do the trick

In the real world I'd probably find it quicker to use a microcontroller though

Talk about over engineering a solution, although a 556 has most of that on one chip.

Burnsy

BenST · 3 Aug 2007 at 21:01

A helpful gent from another forum posted this solution using NAND gates;

It works fine with a LED however I'm having much trouble trying to get it to trigger a relay. I think the transistor I'm using doesn't have a high enough HFE. The resistor coil is 250 ohms and AFAIK the max output of CMOS logic is 1mA?

Any help appreciated!

Six6siX · 3 Aug 2007 at 21:03

Darlington pair to boost gain?

Burnsy2023 · 3 Aug 2007 at 22:49

Six6siX said:
Darlington pair to boost gain?

Or a simple transistor switch should do it. You don't need a lot of current to energise a 250 ohm coil.

Burnsy

Tomsk · 3 Aug 2007 at 23:34

You can actually buy a timer relay that will do what you want - Omron H3DE