I have two PCBs - one with a couple of voltage regulator and a series of MOSFETs to drive strip LEDs (pcbA), the other for a Nano Every and LCD (pcbB).
When the two boards are connected together and the powered through the Arduino from my PC, or if the pcbB is powered from a wall-wart via the voltage regulators on pcbA, the reception of my DAB (digital radio) drops out.
With the same arrangement, except the Arduino being powered from a USB battery pack rather than the PC, the DAB reception is fine.
When pcbB is powered from my PC but pcbA isn't connected, the DAB reception is ok.
In all of my tests (so far), the strip LEDs have not been connected to the outputs of the MOSFETs.
It seems to me that the issue is likely either the MOSFETs (possibly due to unconnected outputs) or the voltage regulators. But changing the USB powering is confusing.
This is a simplified version of pcbA. (The full version has repetition of the MOSFETs, LED strips rather than a descrete LED, and some resistors for inpuits to the Arduino, but they’ve not been connected to anything when I’ve been getting the problem.
None of the example circuits I’ve seen that do the something similar have had capacitors on the MOSFETs. Should there be?
When my Arduino/MOSFET circuit is powered up, I get clear reception of the digital radio station. When I power up the circuit, the receiver goes quiet. If I them disconnect the Arduino/MOSFT circuits from power, the radio starts outputting audio again. If that’s not indicative of RF interference, what are you suggesting it could be?
@gilshultz Voltage at J3 is 12v DC from a wallwart. Nut I get the same interference when the circuits are powered via the arduino's USB port and nothing connected to J3.
All the grounds on each board are connected, and when both boards are running together, the grounds of both boards are connected together.
(Can't see your link to a data sheet. Maybe that just on my phone. Will check on a PC tomorrow.)
Your led is upside down...
What type of strip led du you use?
6V seems odd...
And why regulate to 9V for arduino?
Whare is the DAB connected snd powered?
What type of arduino?
@build_1971 I first noticed the problem when the only power source was USB power to the Arduino Nano Every and nothing was connected to the barrel, so the only voltage the regulators wer supplied with was 5v at their outputs.
(I’ve replaced the schematic above with corrections, which should address a couple of your other questions.)
@TomGeorge The DAB is mains powered and works fine when sited further away.
