Toggling Lights with a push button

Thread Starter

teenflon5

Joined Apr 19, 2021
5
Hello,

I'm working on a little project to power some old Airbus overhead lights using LEDs and the built in push buttons, however I'm a little stuck on the solution for this.

Essentially the unit has momentary push buttons for toggling the lights on and off. I intend to power some LEDs and toggle them on and off using the existing buttons, but I dont know the right approach.

I tried thinking of using an S/R latch to toggle the LEDs on or off, however connecting the S and R pins to the button at the same time didnt really work, I tried putting some gates in between but that just made things worse!

There must be a simple solution to toggle an output based on pressing momentary push buttons but I'm not aware whats out there. Is there a simple IC or component that can do this?

Thanks
 

Yaakov

Joined Jan 27, 2019
3,153
You need a bistable multivibrator—that is, a flip-flop. Or, a latching relay.

The advantage of the latter is that power is not consumed when except to change state.
 

crutschow

Joined Mar 14, 2008
27,190
With a flip-flop, you also need a debounce circuit to ignore any contact bounce from the mechanical push-button switch.

LTspice simulation below, of such a circuit using a FF, as mentioned in posts 2 and 3:
R1C1 delays the feedback to the D input (red trace) which prevents more than one output change-of-state (green trace) per button push (as shown by the simulated switch bounces for the first push (yellow trace).

1621947968717.png
 

Ian0

Joined Aug 7, 2020
2,192
You can do it with a couple of inverters (or nand gates or nor gates) like this:
Untitled 1.pngThe switch is a momentary type. (I couldn't find the right symbol in SPICE)
 

eetech00

Joined Jun 8, 2013
2,350
Hello,

I'm working on a little project to power some old Airbus overhead lights using LEDs and the built in push buttons, however I'm a little stuck on the solution for this.

Essentially the unit has momentary push buttons for toggling the lights on and off. I intend to power some LEDs and toggle them on and off using the existing buttons, but I dont know the right approach.

I tried thinking of using an S/R latch to toggle the LEDs on or off, however connecting the S and R pins to the button at the same time didnt really work, I tried putting some gates in between but that just made things worse!

There must be a simple solution to toggle an output based on pressing momentary push buttons but I'm not aware whats out there. Is there a simple IC or component that can do this?

Thanks
Questions:
1. Supply voltage?
2. Output Load (LED current/voltage)?
3. Two buttons or one (for each LED)?
4. button type (1NO?, 1NO+1NC?) or?
5. Retrofit existing wired buttons and LED's? or new?
 
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