What has to be changed to increase the variable time the relay is energised up to 30 seconds?



Mod edit:
Please don't hijack other member's post, now you have your own.

This thread was split from -- The old guy.
http://forum.allaboutcircuits.com/threads/new-old-guy.109561/page-2#post-910966

 

I see two circuits in that older thread. Which one are we talking about here?

You could increase C1 or one of the timing resistors.

 

What has to be changed to increase the variable time the relay is energised up to 30 seconds?

30 seconds is a long time for a 555 timer if you need it to be accurate, but you can use this graph:

 

http://www.ohmslawcalculator.com/555-monostable-calculator

ak

 

The capacitor needs to have a very low leakage to achieve a delay time that long.