I was a real pain. The product was designed based on the Philips (HEF) Datasheet. Only when we had bought a batch of SGS-Thomson parts (HCF prefix) did we find that they were different, and from then on we had to check every quote to make sure that the supplied had not substituted parts from a different manufacturer, especially when all the other 4000 series was "don't care" as far as manufacturer was concerned.

 

No

It is possible using a 555. Here's a version that requires 2 additional transistors.
Keep in mind it only works with brief pushes of the switch.
View attachment 227580

hello. Thanks for the help. This circuit resets the timer. When I press the button i.e led starts glowing from t=0. I want to switch off the led on second button press. Maybe I am doing something wrong. here is screenshot to my simulation circuit.

 

That's not how my circuit is drawn. I have no connection on DIS or THR. What's the purpose R1 and C3?

 

That's not how my circuit is drawn. I have no connection on DIS or THR. What's the purpose R1 and C3?

It will decide the time of the output of the monostable timer. In your circuit, How will you decide the time for which output will stay 'HIGH' when you press the button ?

 

It will decide the time of the output of the monostable timer

The second push of the button decides that. That's what you requested.
Remove C3 and R1, disconnect pin 6 from pin 7 as shown below.

 

The second push of the button decides that. That's what you requested.
Remove C3 and R1, disconnect pin 6 from pin 7 as shown below.
View attachment 227724

what will happen if I don't press the button second time?? will timer end after let's say 15 seconds ?

 

what will happen if I don't press the button second time?? will timer end after let's say 15 seconds ?

No. It will not shut off until the second press.

 

No. It will not shut off until the second press.

sorry friend. That's not what I had in mind. Thanks for the time and effoirt

 

I apologize I did not read your first post correctly. I now see you want the circuit to shut off after a certain amount of time
Then reconnect as before.

 

The problem with your circuit is the value of R1, it's too low.
For appx. 15 sec. change C3 to 100uf and R1 to 150K.

 

I apologize I did not read your first post correctly. I now see you want the circuit to shut off after a certain amount of time
Then reconnect as before.

yes. but that's not working. timer gets triggered but not resetting.I also asked here . got some solutions. tried them. NO success. still trying

 

The problem with your circuit is the value of R1, it's too low.
For appx. 15 sec. change C3 to 100uf and R1 to 150K.

that's not the problem. time is just a variable. R1 and C3 can be managed easily.

 

How soon is it resetting?
Did you reconnect the circuit as you originally posted?

 

How soon is it resetting?
Did you reconnect the circuit as you originally posted?

it's not resetting. You can access my circuit as well. I think. Go here and search "sahil_siwatch_007"
and yes. I reconnected as I posted.

 

it's not resetting. You can access my circuit as well. I think. Go here and search "sahil_siwatch_007"

 

Have you actually tried building the circuit?

 

Have you actually tried building the circuit?

I have worked a bit with timers but currently I have a timer made on PCB. I usually try simple circuits directly on PCBs

 

So you are saying you have not actually constructed this circuit.

 

So you are saying you have not actually constructed this circuit.

NO. because I don't have DIP package of 555 right now. I usually simulate circuits and then try them on hardware. It works for me most of the times.

 

I don't see anything wrong with the circuit
I don't know why it's not working in your simulation