Dual NE555 sequential timer

[Jantoven]

javascriptpenreq('

http://www.ortodoxism.ro/datasheets/philips/NE_SA556_2.pdf')

Hi all,

I built the sequential timer circuit on page 5 of the PDF link above. It is almost what I need but not quite. The 2 pulses are too close together. I need a two 0.5 second long positive going pulses separated by 0.5 sec off. The pulses in the circuit as shown are one after the other and too close together. Can anyone suggest how I might modify the circuit to add a 0.5 second delay between the 2 pulses? I am using 1 meg ohm and 1 uf for R and C.

Thanks,
Jan

 

[MikeHalloran]

The 555 was a great chip, 20 years ago. Now, not so much, because you have to do so much soldering and other screwing around to make 'em do what you want.

Throw out the 555, and use a low end PIC. It's cheaper, needs fewer external parts, is capable of much more complex behaviors, and is much, much easier to program.

If programming in assembly intimidates you, use a Basic Stamp instead. The cheapest version will do just fine.



Mike Halloran
Pembroke Pines, FL, USA

 

[jimkirk]

Without getting into the 555 versus PIC debate, you can extend the one one-shot triggers the next one idea indefinitely. Add a third timer section and use the first and last one for your output pulses, the middle one will determine the delay between them.

 

[fsmyth]

There are a few examples of delayed pulse timer
circuits, and timing calculations here:

http://people.consolidated.net/fsmyth/pages/2cd_page.html