Hi all,
I'm currently trying to figure out how I could achieve the following by hardware only (no microcontroller to be used), maybe using a 555?

A button is used to trigger. No matter how long this button is pressed, an LED should light up for a predefined period of time (e.g. 1 second) and then switch off again. Only when the button is released and then pressed again, the LED should light up again for the set time. If the button is held for an indefinite period of time, the LED should only light up once for the set time.

Would be really great if someone could point me here in the right direction.

Thanks!

 

Welcome to AAC!
Search for '555 monostable'. Be aware that the 555 is not suitable for setting very long times.
How long is the set time?

 

Welcome to AAC!
Search for '555 monostable'. Be aware that the 555 is not suitable for setting very long times.
How long is the set time?

Thanks!
Wouldnt 555 Monostable retrigger if the button stays pressed?
Basically I need it to trigger only once on the falling edge.
Set Time would probably be around 0.5-1seconds

 

You want something like this circuit, put your switch between A and Ground, that way the timer will give you one pulse per switch press, if the switch is held down continually the timer will just just give one pulse until the next press.

 

Below is the simulation of Dd's basic 555 circuit.

Note that the output pulse width (red and yellow traces) is the same for a short or long button press (green trace).

C3 is connected to V+ instead of ground so that the circuit will still work even if the capacitor becomes leaky (although the pulse period would be shorter).

The pulse width is basically independent of the supply voltage.
The main change is the LED current varies with that voltage, so the value of R3 must be changed accordingly.

 

The circuit to deliver the requested function is a NON-retriggered monostable. The 555 is able to be connected that way. There are also CMOS IC devices that contain two of them in a 16 lead dip package.

 

The 555 is able to be connected that way.

See post #5.