Simple timer circuit wanted
- Thread starter Dtsteam
- Start date
If you're happy with trying some elctronics, you need a 55 timer chip. Have a look at this page
http://www.doctronics.co.uk/555.htm#astable < Link To
http://www.doctronics.co.uk/555.htm#astable
or do a google for "555 timer". If you can't handle elctronics, try googling for "electronic timer". Here's one I found quickly...
http://www.quasarelectronics.com/delay-timers.htm < Link To http://www.quasarelectronics.com/delay-timers.htm
http://www.doctronics.co.uk/555.htm#astable < Link To
http://www.doctronics.co.uk/555.htm#astable
or do a google for "555 timer". If you can't handle elctronics, try googling for "electronic timer". Here's one I found quickly...
http://www.quasarelectronics.com/delay-timers.htm < Link To http://www.quasarelectronics.com/delay-timers.htm
David, try the circuit below.
The supply should be about 12V DC.
The on time is adjusted by RV1 and the off by RV2. For the values quoted the theoretical max for each is approx 175 seconds and the minimum 23 seconds with 100 seconds about the mid point of the adjustment. The tolerance of the electrolytic C2 tends to be quite wide so the actual times can vary a bit. Also you may find that the first cycle is a little longer than subsequent ones.
Edit, I see Greg had the same idea, it took me a while to do the drawing.
The supply should be about 12V DC.
The on time is adjusted by RV1 and the off by RV2. For the values quoted the theoretical max for each is approx 175 seconds and the minimum 23 seconds with 100 seconds about the mid point of the adjustment. The tolerance of the electrolytic C2 tends to be quite wide so the actual times can vary a bit. Also you may find that the first cycle is a little longer than subsequent ones.
Edit, I see Greg had the same idea, it took me a while to do the drawing.
Dtsteam said:
David found this at maplins any good? MK111 Adjustable Timer with Relay Output[/h1] only £5.99
Order Code: VT27E
In Stock*
Thanks for your help guys - looking at the options, I'll probably dip my toe in the water and try some electronics - the maplin kit first, then one of the circuits. Especial respect to Neil for the drawing - clearly a fellow insomniac at work.
Philbahn said:
IMHO it may be O.K. but will need modification as according to Maplins "pulse time adjustable between 0.5 and 5s
Pause time adjustable between 2.5 and 60s"
I think David wants times of around 60s to 120s for both. The values in my diagram give an approximate range of 23s to175s.
I use the adjustable interval timer as supplied by Maplin. By increasing RV1 and RV2, I have had the timers working for over three minutes.
[SIZE=3 font="times new roman"][/SIZE]
[SIZE=3 font="times new roman"][/SIZE]