perhaps it’s better.
Opto input and usb cube power input.

I guess we can just let the TS decide which he prefers.

 

I guess we can just let the TS decide which he prefers.

 

Yes.
It would eliminate a resistor and capacitor on the CD4093 circuit, or allow the use of a simple 555 one-shot circuit.

Finally got around to trying this circuit and yes it works as it should, however with a minor problem. I changed R1 to 200K to increase the time ON but once power is removed the charge on the C1 takes a very long time to discharge. Meaning if you apply power before C1 is completely discharged the circuit does not work as expected.

 

Install a reversed biased diode across R1.
Anode to ground.

 

Install a reversed biased diode across R1.
Anode to ground.

And if necessary, depending upon the impedance of the Vb source when off, also a 10kΩ resistor from Vb to ground.

 

25 posts and no one has suggested an Arduino or PIC. Really, guys . . . Sooooo disappointing - !

ak

 

Usually when someone requests a simple circuit (see post #1) they mean without using a micro.

 

Usually when someone requests a simple circuit (see post #1) they mean without using a micro.

The sarcasm sensor is weak with this one.

 

Usually when someone requests a simple circuit (see post #1) they mean without using a micro.

And usually that has absolutely no effect on ***some*** people. Hence my tagline.

ak

 

25 posts and no one has suggested an Arduino or PIC.

Actually using a micro was suggested by eetech00 back in post #11 albeit it was already assembled.