I’m creating a circuit and one of the controls is a tactile SPST switch where the common is connected to VDD. What I’m trying to do is to have some SPDT where its common is connected to a multiplexer’s select and the NC and NO are connected to VDD and GND, respectively. I’ve been trying to figure out a way to control this MUX with just the SPST tactile switch in a way that the SPDT will switch any time there is a HIGH signal from the SPST. Any ideas?

I’ve thought about using latches to store the latest value but I’m not sure how to implement my idea with just a physical SPST and switch IC’s. I’m looking to explicitly only have one physical tactile switch that every time you press it, changes the analog SPDT direction.

TL;DR How to create an analog latching SPDT that switches anytime an SPST, connected to VDD, is pressed.

  • 1
    \$\begingroup\$ What you want is conceptually a toggle flip flop, the problem is that you need to debounce the pushbutton or it will toggle a random number of times on each push. This can be done with a blanking timer but is often easiest in MCU software... \$\endgroup\$ – Chris Stratton Apr 13 at 3:52
  • \$\begingroup\$ I’m creating an analog circuit with no processing/code, just straight digital logic, I don’t know how that would work with what you’re mentioning \$\endgroup\$ – Anthony Benitez Apr 13 at 3:55
  • \$\begingroup\$ It would work inelegantly - there's a reason tiny inexpensive 6 or 8 pin MCUs get used for this in real world problems. If you really want to do it the hard way, you probably want some sort of timer circuit which generates one long pulse for each button push (but won't re trigger until the end) and then use that to feed a toggle flip flop. \$\endgroup\$ – Chris Stratton Apr 13 at 3:59
  • \$\begingroup\$ RC Debouncer with Schmitt Trigger maybe if you're using push button? Also, some people like me doesn't understand directly what do you mean by just words, you could draw the schematic using built-in CircuitLab or do simulation with falstad. \$\endgroup\$ – Unknown123 Apr 14 at 10:23

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