I have made up a very simple timer to enable an LED to continue to run on after the switch has been opened.
I would include the diagram but don't know how to attach it.
When the switch is closed a capacitor is charged through a low resistance, the current is also fed to the base of an NPN transistor which switches an LED.
When the switch is released the capacitor continues to discharge into the base of the transistor keeping the LED running untill the capacitor is discharged.
The only problem is the LED fades away. I want it to switch off cleanly, I expect this is possible using a 555.
Could someone please post a circuit.
I would include the diagram but don't know how to attach it.
When the switch is closed a capacitor is charged through a low resistance, the current is also fed to the base of an NPN transistor which switches an LED.
When the switch is released the capacitor continues to discharge into the base of the transistor keeping the LED running untill the capacitor is discharged.
The only problem is the LED fades away. I want it to switch off cleanly, I expect this is possible using a 555.
Could someone please post a circuit.