Servo Multiplexer select dead?

I’m having trouble with my 4 channel servo multiplexer. I used it for a project two years ago and I think it worked (I have enough trouble remembering last month, let alone 2 years ago), but now it is giving me trouble. The master channels all work, but I can’t seem to get the select input to select the secondary inputs. I checked my signal with a servo and it looks fine, I also checked with my 'scope and the input goes from 1.1 ms to 1.9 ms at about 3v. Any ideas what is wrong? I could have blown something out I suppose, but the master works and the default jumper seems to do what it is supposed to do (detect an invalid signal – it is always invalid apparently). Am I doing something wrong?

Also, it would be really cool if there was a way to use a logic signal (in place of or in addition to the PWM signal) to select the inputs. It seems like that would be a fairly simple addition (Pololu?)


Hi, Ted.

Could you please post some pictures of your setup including all connections? Also, could you tell me what the LEDs are doing?

We appreciate your feedback regarding the logic level signal. What makes this multiplexer special is that it has the RC input. If you want a digital signal to select one of two inputs, you can use a quad 2 channel multiplexer in a DIP package; here’s one example: … 000270.pdf