replace a potentiometer with button switch array

Thread Starter

seayaker

Joined Jan 27, 2009
54
How to make a 32 button array to replace a potentiometer. If instead of a 10k potentiometer I want to have 32 momentary button switches with leds in each switch, so that the button pressed stays lite untill another button is pressed and lite. Any examples or schematics would be appreciated.
 

crutschow

Joined Mar 14, 2008
23,542
Below is one radio push-button type circuit to perform that function, discussed here.
It can be readily expanded to the 32 buttons you want (3 buttons shown).
32 stages requires 1 capacitor, 1 MOSFET, 66 resistors, 32 diodes, and 16 CD4011 NAND gate packages.
You could reduce the IC count to 8 packages by using the CD4044 quad NAND latch in place of the NAND GATES.

If operated from a higher voltage, such as 12V, the output can drive a low-current (several mA) high-brightness LED directly (with suitable LED series resistance).
Otherwise a MOSFET driver, such as a 2N7000 could be added at each output for the LED.

 
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Analog Ground

Joined Apr 24, 2019
170
I propose the functions in the block diagram for a potentiometer replacement. 32 buttons in and a voltage out. The interesting part is how to combine the encoding with the mutually exclusive latching function in an optimal way.

ButtonEncoder.jpg
 
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danadak

Joined Mar 10, 2018
3,630
One possibility, single chip -

upload_2019-6-20_15-42-10.png




Note did not use much of the chips resources, right hand column shows used/left.

Also I did not look into this but might be possible to use Capsense matrix instead of
mechanical buttons to get rid of external hardware buttons.



Lastly I drove LEDs directly, you could put them in a matrix also to save pins.

This is Cypress PSOC.


Regards, Dana.
 
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