Wired as per the tutorial. Powered with 5V from SparkFun RedBoard. Used without and with 220 Ohm/100uF RC-circuit on VCC. Using the AUDIO output to A0.
-
Without RC-circuit, the noise floor is rather high in silence and with sound, which ain’t good
-
With RC-circuit, the noise floor is very low in silence, which is very promising
-
With RC-circuit, once a loud noises is made, the LED remains on and A0 values oscillate on a high level until power is removed
What can I do? I obviously much prefer the low noise RC-variant. Thanks!
Even with the RC-circuit, there might still be some power supply noise that’s causing the LED to remain on and affecting the A0 readings. You can try to add additional filtering to the power supply, such as capacitors across the power rails or using a voltage regulator to provide a cleaner power source.
@ Systembolaget - Reading the documentation for the SoundDetector board it is pretty clear that the circuit is very sensitive to noise or fluctuations on the power rail. That is inline with what you seem to be trying to address with this RC network and with suggestions from @aliarifat794. It is not clear to me what you describe when you state an RC circuit on the power rail but I must presume is a series R with shunt C between the power supply and the SoundDetector board. Can you illustrate in a diagram where that RC is being applied?
I would suggest, just like the documentation, that you power the board from the cleanest supply you can. If you are supplying from Redboad +5v regulator output, ensure you are not driving Redboard from USB but rather the higher voltage input (i.e. +7V or more) so the Redboard regulator is in the picture (just like the documentation suggests). If you can’t do that, use batteries to isolate the power supply. Bottom line is that you may need a regulator to clean-up the supply to get you the desired performance. I would certain not suggest using a series R shunt C to attempt to clean up the supply. The SoundDetector analog circuit seems way too sensitive for that type of circuitry (i.e. a series R on the power line).
Thanks, I’m using an external 5V 2A wall-PSU like for most of my projects. Maybe I can find a 7V 2A wall-PSU, if that’s necessary for the Sound Detector board. Maybe the noise floor goes down. Can’t use batteries, unfortunately.
Keep in mind that the battery example was not meant to be a long-term solution but rather a means of troubleshooting by isolating the power supply as the source of issues.
This section of the guide is what I was referencing:
In testing with various supplies, a significant degree of variability was discovered - some supplies are less noisy than others. One exhibited as much as 30 mV ripple on the supply output, an as a result, the the Sound Detector was rather sensitive and unstable. You can check how clean a power supply is by checking it with an oscilloscope or volt meter, set to the AC Volts (or, if provided, the AC millivolts) range. A truly clean supply will show 0.000 VAC. Based on the supplies used in testing, ripple of more than about 10 mV is problematic.
Powering my Arduino with a 9V external supply, which allows the onboard regulators to function, the Arduino’s 5V output was sufficiently clean. However, powering it from the 5V available on the USB port on a PC, the regulators are bypassed, and the results were somewhat less usable, and vary greatly between different ports on different PCs. A powered USB hub will probably provide cleaner power than the ports on the PC itself.
If all else fails, three 1.5V batteries in series make a nice, clean source of 4.5V.