hi,
In addition to the WB guidance I would increase the 10n [C3], connected to the 100k[R3], to say 47n, also add a signal diode in parallel with the 100k.
Diode Cathode to the +8V supply.
E

 

Thanks @WBahn and @ericgibbs!

And if I would like to have this certainty about initial OFF state in my design, any idea or suggestion?

Thanks again for your time!
Regards,

 

hi Isi,
This Sim shows the power ON Reset pulse, I have increased the Cap value to 100nF and shown the diode across the 100K.
I prefer using a CD4093 [Schmitt Input] for mechanical switching.

E

 

@ericgibbs @WBahn
When I said "my design", I meant post #47.

Thanks!
Cheers

 

Thanks @WBahn and @ericgibbs!

And if I would like to have this certainty about initial OFF state in my design, any idea or suggestion?

Thanks again for your time!
Regards,

Why don't you have certainty now?

If you want more certainty, replace C3 with a physical switch that is closed when you turn on power and then open it when you are ready for the circuit to start functioning. Or get rid of U1 and U5 altogether and connect the bottom input of U2 to the anode of D2 (I'm referring to the schematic in Post #63) and a switch between that node and ground, again having the switch closed when you turn on power. There are other options as well.

 

@ericgibbs @WBahn
When I said "my design", I meant post #47.

Thanks!
Cheers

hi,
I assumed that you were using EM Fields design, have you made a decision on the version of the circuit you are planning to use.??
Consider using a link from the 'arm' switch to the bistable circuitry.

E

 

Why don't you have certainty now?

If you want more certainty, replace C3 with a physical switch that is closed when you turn on power and then open it when you are ready for the circuit to start functioning. Or get rid of U1 and U5 altogether and connect the bottom input of U2 to the anode of D2 (I'm referring to the schematic in Post #63) and a switch between that node and ground, again having the switch closed when you turn on power. There are other options as well.

@WBahn ; I am referring to another schematic, post #47.
Thanks anyway for the explanation!

 

hi,
I assumed that you were using EM Fields design, have you made a decision on the version of the circuit you are planning to use.??
Consider using a link from the 'arm' switch to the bistable circuitry.

E

Hi @ericgibbs,

So far, I am going to use the circuit post #47. I will see how I could force the initial OFF state.

Cheers,

 

hi Isi,
OK.
Consider an additional 2N7002, with it's Gate connected to the high side of the 'arm' switch.
Use the FET to clamp the Reset pin to 0V while the 'arm' is switched to OFF.

BTW: Using a LTS Sim switch with an Off resistance set for 1meg ohm. will not switch off the M1 FET for a simulation run, change it to 10meg.
Do you follow OK.
E