Pin 7 of 555 timer doesn't discharge

[chopnhack]

Any suggestions on getting a long time constant using this 555 timer?

Could we not simply gang a series of 555 timers with the input trigger of the next stage be tied to the output of the previous? Thus we increase the max constant with each added chip - cumbersome in comparison to a pic, but way simpler for an experienced analog fella to follow.

 

[CDRIVE]

Could we not simply gang a series of 555 timers with the input trigger of the next stage be tied to the output of the previous? Thus we increase the max constant with each added chip - cumbersome in comparison to a pic, but way simpler for an experienced analog fella to follow.

I've mentioned this before but it's worth repeating. Once upon a time when TTL was the hottest new logic, a company (I think Maxim) manufactured an IC that incorporated a 555 and two decade counters. Using that chip I built timers with delays in HOURS!

Regardless of that; yes, you're correct. He could do that.

Chris

 

[(*steve*)]

Using that chip I built timers with delays in HOURS!

There is a CMOS equivalent too

 

[CDRIVE]

There is a CMOS equivalent too

You mean they're still manufactured?

Chris

 

[(*steve*)]

The 4060 is an example.

Perhaps the term "equivalent" was possibly not wisely chosen.

 

[Alec_t]

I second the CD4060 approach. It could drive a logic-level power FET directly, but a buffer transistor would be needed for that IC to drive a relay.