Thanks. But is it not possible to make a circuit with LMC555 and IRLZ44N, that triggers when conncted to GND ?

 

Thanks. But is it not possible to make a circuit with LMC555 and IRLZ44N, that triggers when conncted to GND ?

Working on it.

 

Version #2
Drawback: must release Sw1 within a second after the LEDs turn ON and when turning OFF.
Circuit not verified. Currently traveling.

 

Thanks. But is it not possible to make a circuit with LMC555 and IRLZ44N, that triggers when conncted to GND ?

Don't think it's possible without adding another active device, as sghioto's circuit shows.

The Post #12 circuit uses just one IC package.

 

A circuit with the least parts would likely be a small PIC microcontroller driving a MOSFET switch.

Do you happen to have an example of such a circuit? I’m looking to create my first microcontroller project. It is a simple timer for an enclosed UVC source triggered by closure of the box door with possibly supervision of voltage and charging of a lithium battery or two.
However I am completely overwhelmed with the choices of microcontrollers available and the amount of excessively detailed information available online. It’s literally like drinking from a firehose.
Where to start?

 

Version #2
Drawback: must release Sw1 within a second after the LEDs turn ON and when turning OFF.
Circuit not verified. Currently traveling.
View attachment 344411

What if I pulled the button to high with a 100k resistor ?

 

What if I pulled the button to high with a 100k resistor ?

OK

 

OK

Would #23 then work ?

 

It should work as designed in #23.
Making R1 100K doesn't change the operation.
Increasing the value of C1 will allow holding the switch down longer before releasing.
The LEDs will come as soon as the button is pressed but if the switch is held down for more then second or so the LEDs will then shutoff.
1 second is actually a fairly long time for a button push.

 

It should work as designed in #23.

I could not get its sim to work, as the TRIG input (pin 2) and the RES input (pin 4) both go low when the output is high and the PB is pressed, so the output only goes low only for the time the PB is pushed.
Can you explain how you expected the circuit to work?

 

It should work as designed in #23.
Making R1 100K doesn't change the operation.
Increasing the value of C1 will allow holding the switch down longer before releasing.
The LEDs will come as soon as the button is pressed but if the switch is held down for more then second or so the LEDs will then shutoff.
1 second is actually a fairly long time for a button push.

Sorry, you are right

 

I could not get its sim to work, as the TRIG input (pin 2) and the RES input (pin 4) both go low when the output is high and the PB is pressed, so the output only goes low only for the time the PB is pushed.
Can you explain how you expected the circuit to work?

View attachment 344538

Q2 should not conduct until C1 charges to enough voltage thereby not providing a ground the RES is the idea.

 

Q2 should not conduct until C1 charges to enough voltage thereby not providing a ground the RES is the idea.

Yes, but the Trig input goes low at the same time so the output goes back high when the PB output goes high, as the sim shows.

 

Q2 is supposed to remain conducting long enough to keep the res low while the trigger is pressed turning off the 555.

 

Q2 is supposed to remain conducting long enough to keep the res low while the trigger is pressed turning off the 555.

Yes but the Trig input is also low and its trigger level is higher than the Reset threshold, so it turns the 555 output back high as the PB signal goes back high.

 

I could not get its sim to work,

The reset pin has to stay LOW longer then the button press to reset the 555. which is a LMC555 BTW.
Modified version adding C2 for additional delay with R2 at 1M.

 

Modified version adding C2 for additional delay with R2 at 1M.

Sorry, still no cigar.

 

That's not the circuit I posted in #36.

 

That's not the circuit I posted in #36.

Oops!
But still no workee.

 

Oops!
But still no workee.
Try one more thing please.
Add a 250K resistor from pin4 to ground.