Pololu Mux #721, #2806, schematics/slave power

I have a few discontinued Pololu 4-ch RC multiplexers, item #721, which were replaced with #2806.

I have two questions:

  1. Can someone confirm that on the newer multiplexer #2806, the power pins S1-S4 are connected? This isn’t true for item #721, the power pins on S1-S4 are not connected (at least on my boards, which i tested with a multimeter). I planned to distribute power over the slave pins as this will simplify my design, I think I will buy a few of the new multiplexers but I wanted to confirm before buying.

  2. Are the schematics for item #721 and #2806 available somewhere? I could not find them through the webpage / google, having the schematic would have saved me some trouble.

Thanks all!

Hello, Revamped.

The power pins of the S1-S4 inputs are connected to each other on the VS rail but are separate from the board’s power (VM). You can also access the slave power through the extra access pins. You might find this picture from the product page helpful.

We do not have the schematic for the old RC servo multiplexers available. However, we just uploaded the schematic for the new 4-Channel RC Servo Multiplexer in the RC switch user’s guide

- Jeremy

Hi, I got similar issue on item#: 2806.
What kind of signal expected to let Mux switch to S1/S2 PWM?
I tried to tir SEL_signal to high or low, but it always select the M1/M2, not S1/S2.
How to force OUT1/2 from S1/S2?


The RC multiplexer measures the width of incoming RC pulses on the SEL channel to decide whether the master (M1–M4) or slave (S1–S4) inputs should show on the output channel, so a constant high or low signal are invalid signals. You can find more information about this in the product page description and the RC switch user’s guide.


Can SEL pulse width be adjustable or set different threshold, I.e. set 2ms width, > 2ms M1-4, < 2ms S1-4?


Yes, you can adjust the threshold by following the instructions in the “General Configuration Procedure” section of the user’s guide.