Hi all
I wanted a LED to come on when a bell switch is pressed, and then it must automatically switch off after 2-5 minutes.
I would appreciate you taking a look at the attached circuit. When the switch is pressed, a capacitor is charged, which feeds the base of an NPN transistor, which switches on the diode. It works fine, and the LED slowly fades till its off. The size of the capacitor determines the time on.
If you can suggest improvements to the circuit, maybe to use less current, or have the LED maintain brightness and then snap off, it would be appreciated.
I wanted a LED to come on when a bell switch is pressed, and then it must automatically switch off after 2-5 minutes.
I would appreciate you taking a look at the attached circuit. When the switch is pressed, a capacitor is charged, which feeds the base of an NPN transistor, which switches on the diode. It works fine, and the LED slowly fades till its off. The size of the capacitor determines the time on.
If you can suggest improvements to the circuit, maybe to use less current, or have the LED maintain brightness and then snap off, it would be appreciated.