removing noise from the 5v power rail
Turbo Mini Forums

as some of you know i have fitted a bluetooth module to my MS3 ( and have another waiting for the mini's MS2)
anyway long story short i found out it it was putting a fair bit of noise onto the 5v power rail, and this was causing havoc with everything that referenced 5v ( temp sensors and tps)
so i brushed up on power supply regulator circuits and what i have ended up doing is put an electrolytic capacitor across 0v and 5v (2200uf) probably overkill but it worked

what im wanting to know is- is this acceptable as a long term thing? would anyone recommend a different type of capacitor or a different method ( i thought about another 5v reg circuit but would this be better?)

any input appreciated

Yes i moved to the darkside

Instagram @jdm_brett

The best solution would indeed be a separate 5V regulator in my opinion. The cap will lower the noise consistently but having more load on the original regulator circuit will put more into the circuit and that may mean a small voltage offset when the bluetooth module is working.

If you don't see any noise or voltage variation whether the module is running or not then you can keep the simple capacitor solution. If you see anything or want to make sure it doesn't happen, use a separate circuit.

Jean

http://www.jbperf.com/

a big cap will certainly bleed noise down to ground, but its good practice to try to stop it with an inductor, something like 1uH between the 5v rail and the BT board, and put a cap at each end of the inductor. something like 22uF.

another possibility is the BT board radiating into the other circuits, but it should be ok.

having the bt module powered up isnt what is causing the noise its when its paired and talking to Tuner studio / MSdroid
it drains about 10ma more when the module is paired this is when the noise starts, i think what i will do is both, a separate reg with the inductor and caps

Yes i moved to the darkside

Instagram @jdm_brett