I don't understand how i can eliminate the voltage peak at startup. This Peak causes the output of the first TLC55 to get high. But i just want to trigger the switch not the startup? Does this happen only in LTSpice?View attachment 370740

 

Maybe, try this:
Connect a 1uf cap from pin4 to ground and a 100K resistor from pin4 to VDC.
BTW, you can make that circuit with a single TLC555.

 

Hi Code
Please post your LTS asc file.
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Try connecting C4 to VDC instead of ground.

What is the purpose of U1?
It does not seem to be needed, as U2 can be triggered directly from S1.

 

Try running with the startup transient option instead of uic, which more closely simulates a power supply startup.

 

Try connecting C4 to VDC instead of ground.

What is the purpose of U1?
It does not seem to be needed, as U2 can be triggered directly from S1.

The U1 is triggered by a constant or fluctuatingsignal the U2 is giving a 1 second impulse

Maybe, try this:
Connect a 1uf cap from pin4 to ground and a 100K resistor from pin4 to VDC.
BTW, you can make that circuit with a single TLC555.

doesn't change anything

Hi Code
Please post your LTS asc file.
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Thank you for the advise. I'm not so familiar with LT what shows the asc what cannot be seen on the Screenshot? How can i work with the asc file?

 

hi Code,
This is what I see in a LTSpice simulation.
What problem do you see in your simulation??
Note I have added measure point labels p1,p2,3.

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Try running with the startup transient option instead of uic, which more closely simulates a power supply startup.

This helped for the U1 but now the U2 has the ground peak at startup ? i don't understand it.

 

Hi Code,
Check out this modified simulation.
Note the changes around the p1 source
also added reset R/C to the Reset pins of the 555

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Have you tried breadboarding the circuit?

 

I do not understand why the trigger U2 at measure point p2 takes so long to get high in the beginning this causes p3 to get high. I want the U1 out to trigger the U2 and not the start. Does it really takes too long to get the U2 trigger High (p4) at startup and the U2 is setting out (p3)high? How can i change this behaviour?

 

Hi Code,
Download and run the asc file I posted in post #9
You ask:
I do not understand why the trigger U2 at measure point p2 takes so long to get high in the beginning this causes p3 to get high.

The PULSE is only operating the S1 switch, there is no pull up resistor !

Look at my modified circuit.
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added reset R/C to the Reset pins of the 555

You could use just one R/C to both Reset pins.

 

Circuit using one 555 with no startup glitches:
Note the startup transient option which ramps up VDC from zero.