# 4051 MUX as 8-Pole Switch

I am a beginner in electronics so please bear with me if this question seems stupid for you.

I have a circuit that I want to modify at certain points. All in all there are 8 modify points in the circuit and 8 modifications that short these points or place a capacitor in between them. To put it in a nutshell I need to toggle 8 data lines. I thought there were 8-pole 2-throw switches. Unfortunately I could find such switches. I read that a multiplexer would be a good idea.

However I never worked with them. I wondered if this is the right way:

Again sorry if this sketch seems hideous to you. As you can see every 4051 MUX has a modified circuit as an output. So I need eight multiplexers for every modification point. Every multiplexer is controlled by a microcontroller like an arduino. The microcontroller establishes the control sequence based on the output of a 74HC165 shift register. This shift register generates its output by checking which switch is closed.

I couldn't verify this schematic because I don't have the multiplexers yet. Could this work?

• It does not look very efficient with 3 x3 separate control lines. Try to start with a truth table Jun 21, 2021 at 19:27

Here's what the various analog switches in the CD405x family are like:

The CD4051 is a single pole, 8-throw switch. It requires 3 digital inputs to select the position of the switch.

The CD4053 is a 3-pole, 2-throw switch. It uses one digital input per channel to control the positions of the three switches.

By connecting the channel selector inputs together you could use 3 CD4053's to implement an 8-pole, 2-throw switch.

there are 8 modify points in the circuit and 8 modifications that short these points or place a capacitor in between them.

It seems that you could use a SPST switch like this:

If the switch is closed there is a short between A and B. Otherwise there is a cap between them.

The CD4066 contains four SPST analog switches, so you would only need two of them for an 8-pole switch.

Every multiplexer is controlled by a microcontroller like an arduino.

The way you are connecting the control signals from the Arduino to the multiplexers is fine.