Hi I looking for a monostable circuit.
I want it, to complete the time period even if the swicth is hold down constant ..

I have build a Non-Retriggerable Monoflop, but if I hold the swicth down constant, the LED remain on.

Hope any boddy can help me with a circuit, or an idea of what to seach for.

 

Here you go

 

Thanks for reply
I have build it and test it.. It works ..but it seems like it is unstable.. I have to push the swicth 2-3 times before it starts up again.

 

Thanks for reply
I have build it and test it.. It works ..but it seems like it is unstable.. I have to push the swicth 2-3 times before it starts up again.

If your switch is good then change the switch to pin 2 to try and take R1,C1 away .

 

The switch is good. I remove R1,C2 ... and it's the same ..

 

The switch is good. I remove R1,C2 ... and it's the same ..

Do you want to using another switch to try or using wire to replace the switch.

 

Leave R1/C1 as shown; reduce R5 to 1k or less if you need to re-activate the mono quickly.
The mono pulse width needs to be at least 20mS (which is highly likely if you want to see the LED lit!), to prevent re-triggering by switch-bounce transients.

 

R1/C1 is back on. R5 is reduced to 1K ...still the same. We are not talking about quickly re-activate, even if I wait 10 sec. before I pres the swicth again, it behave like that (some time 1 press some time I need to press 3-6 time before it work).

 

try a different switch to see if the one you are using is bad.

 

Okay I found out why it behave like it did.. now it work like af dream .. the reason was because I used a cheap wall supply .. I think it was given some kind of spike or so.
Thanks you all for your help

 

Recheck the wiring and using another 555 to try.
And how is the voltage of V1?
I think the 220 Ω for led is designed for V1 power supply.

 

Okay I found out why it behave like it did.. now it work like af dream .. the reason was because I used a cheap wall supply .. I think it was given some kind of spike or so.
Thanks you all for your help

Because I was used the traditional transformer liner power, so I never happen something like that.

Two 4 kinds ±5~15V fixed power.

 

I just pick one in my pile. I think it original, was from an old tape recorder or similar.
The circuit will be used in a machine I'm building, so that's why I didn't use my benchtop supply.
But now I know how important it is to use a good power supply.

 

now it work like af dream

Good news that you found the culprit and got the mono working.