I have a board with a 60kHz receiver and a 3 digit multiplexed LED display. The multiplex is currently running at 1960.78 Hz.
What would be a better frequency for lower levels of interference?
I will also add more decoupling for the receiver power connection.

 

What is the power source? If it is a SMPS, replace it with a Linear version.

 

What is the power source? If it is a SMPS, replace it with a Linear version.

The power is SMPS but the receiver is OK if I stop the multiplexing oscillator.

 

With 3 digits times 30 Hz, 100 Hz would be the lowest to avoid flicker.

 

With 3 digits times 30 Hz, 100 Hz would be the lowest to avoid flicker.

Would that produce the least interference at 60kHz?
Incidentally, the receiver was salvaged from a clock so is intended to run on 1.5V. I have an LM317 to reduce the 5V to that 1.5V so the receiver has a linear supply.

 

Would that produce the least interference at 60kHz?
Incidentally, the receiver was salvaged from a clock so is intended to run on 1.5V. I have an LM317 to reduce the 5V to that 1.5V so the receiver has a linear supply.

I should think so. Do you have a way to alter the multiplexer clock?
If it is a simple RC oscillator, just put another capacitor across the existing capacitor.

 

I should think so. Do you have a way to alter the multiplexer clock?
If it is a simple RC oscillator, just put another capacitor across the existing capacitor.

I can change it. It is a PIC timer 2. I can get down to 122Hz but that still kills the receiver.

 

I can change it. It is a PIC timer 2. I can get down to 122Hz but that still kills the receiver.

Ok. Then it must be something else besides frequency that is killing the receiver.

 

Fast transitions include harmonics! so if you can slow the transitions in the multiplexer wave forms that should provide some relief. Multiplexed displays have been notorious interference generators which is why many of us avoid them.

 

I have decided to mount the receiver and antenna away from the rest. Just a little bit of 3 code wire...