Greets all;

Its been a while since I played with the 555 timer. I have got one to work with long time periods, years ago (yep, old fart now). Now I need an astable circuit that is on for 1 second, off for 60 seconds, or close to these times. I will figure it out eventually on my own, but I figure some of you are current with 555 timer applications, so I'll ask for your assistance and see what fly's.

Thanx in advance for your help should you reply to this.

Hi again Mike;

I ran some numbers on the circuit you suggested. And with some digging, I found pretty much the same circuit, but your suggestion just looks more reliable...

Anyway, I used the following values and get the given signal specs as follows.
R1 = 280K ohm
R2 = 18.42M ohm
C2 = 4.7uf not electrolytic

Frequency = .016Hz
Duty Cycle= 1.7%
Time High = 1.008 Sec.
Time Low = 60.014 Sec.

If I may ask your opinion once again, do you see any problems with these parameters? I know the resistor values are not stock, other than that, do you think this is a stable configuration?

Thanks again for allowing me to pick at your brains...

I thought there was some sort of limits that are the conventions. I was concerning myself about the timing cap. As I recall, it should not be an electrolytic because the stability of the timer is effected.

Knowing these details, I will go back and try again, attempting to stay within those parameters. As for the relay, yes I am aware of that. I am using a transistor driver circuit anyway because at some future time, a larger relay may be employed. And I am aware of the need to select components that properly saturate the transistor... etc.

Thanks again for your help...