555 delay on monostable

[psymon]

I am at my wits end with these timers.

Im tryin to create a 30 delay on timer using 555 power on ,delay on.

I have this circuit off the net
https://555-timer.clarkson-uk.com/operation/delay.html

When I run it in multisim I have no output what so ever.

questions are:

What happens to pin 7 as it does not appear on the diagram

Does it matter that the cap and resistor are the oppersite way round.

Cheers

 

[Hank Fletcher]

Hmm... it's hard to know where to start with that one, other than to say it's a poor example/diagram for setting up a 555 monostable. Even if you did what it says, I can't see it working.

You need a better explanation/diagram, so I Googled for 555 monostable and found:
**broken link removed**
which has what you need, correctly. Be sure to scroll down to the "monostable" section, there's a good schematic there.

 

[dch222]

Also, I can't see any single 555 circuit giving periods of more than a few minutes due to leakage through the capacitor and the input pins of the 555.

You need to have a more modest period (say 5 seconds) and follow it with a multi-stage ripple counter which divides by 2 lots of times until you get the delay you want.

 

[psymon]

Thanks for the replies guys, please see my other post, as I think this will not work, as i require a delay of 30 prior to an output

 

[Roff]

Thanks for the replies guys, please see my other post, as I think this will not work, as i require a delay of 30 prior to an output

30 what? Seconds, minutes, hours,...?
I simulated the circuit, and it should work fine for 30 seconds. 30 minutes, probably not.

 

[AllVol]

I think this will not work, as i require a delay of 30 prior to an output

If you plug the following values into the calculator at the site you mention,

330 Kohms
100 uF

and enter submit, you come up with a delay of 36.3 seconds before the 555's output goes high. Pin 7 is not needed in a one-shot.

 

[Roff]

If you plug the following values into the calculator at the site you mention,

330 Kohms
100 uF

and enter submit, you come up with a delay of 36.3 seconds before the 555's output goes high. Pin 7 is not needed in a one-shot.

Yeah, well, I calculated that, for 30 years, you could use 10 Megohms and 86 Farads. So there.

 

[AllVol]

for 30 years, you could use 10 Megohms and 86 Farads.

I probably won't be here. PM me if it works.

 

[Roff]

I probably won't be here. PM me if it works.

I see in his other post (with the counter) that he actually specified units of time. I was actually assuming fortnights, but it does appear to be seconds.
So forget the 30 years calculation.

 

[AllVol]

I see in his other post

Yeah, man, it's like a soap opera.... miss one thread and you're doomed!

 

[psymon]

Thanks for all the input guys

I have now managed to solve my problems.....

Thanks again

 

[AllVol]

I have now managed to solve my problems.....

Thanks again

That's very good psymon. However; there are others on this board who may be having problems similar to yours. I am sure they would appreciate knowing how you accomplished getting your circuit to work.

Would you mind sharing with them?