Keep switch closed for N seconds even after the switch contact is open

Thread Starter

bmbouter

Joined May 29, 2021
21
I have a normally open push-style switch which provides current to a LED. What sort of schematic would allow the LED stay on for 30 seconds after the switch was pressed momentarily? For clarity here's an example timeline:

Time | observation
----------------------------
0s | switch is closed
0s | LED turns on
1s | switch is released (open again)
30s | LED turns off
 

ApacheKid

Joined Jan 12, 2015
724
I have a normally open push-style switch which provides current to a LED. What sort of schematic would allow the LED stay on for 30 seconds after the switch was pressed momentarily? For clarity here's an example timeline:

Time | observation
----------------------------
0s | switch is closed
0s | LED turns on
1s | switch is released (open again)
30s | LED turns off
Surely a capacitor and resistor combo could do this? Press switch charges capacitor instantly, releasing switch leads to capacitor discharging slowly through a bleed resistor.
 
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