There is buzzing noise..Did i do anythng wrong with this set up?

[ng501]

An externally hosted image should be here but it was not working when we last tested it.

I am modifying this headset to bluetooth,

so i connect the battery to both bluetooth module and to the headset power ( i believe is for noise cancellation and amp),

switch the audio input from the jack to bt module,

ground both headset amp and audio input together and connect to battery neg-... and when i connect my phone to bluetooth there is buzzing sound coming out! it is fine when i use 3.5mm jack as audio source....

someone tell me put 0.1uf capicitor on both right and left channel between the bluetooth and the headphone driver can filter that sound....is that true or should i use a resistor instead?


Please help! Thanks!

 

[ng501]

any suggestion?

 

[danielwritesbac]

Any suggestion? Okay, here goes with that:
ONE ground wire, only one; because, there is only one ground.

 

[ng501]

An externally hosted image should be here but it was not working when we last tested it.

here is the orginal 6 cable

1)blue for the power positive
2)black for power nag-
3) copper for power ground
4) red audio right
5) green audio lefr
6) audio ground.


do you mean that two ground is a common ground?
so what is the best way to connect these to one battery and a bluetooth module with out the annoying buzzing noise??

Thankss

 

[AndrewT]

Measure the resistance from one ground wire to the other ground wire.
It could be zero ohms, or it could appear open circuit.

 

[ng501]

so where is the noise come from? im newbie,,,,,

 

[danielwritesbac]

Is the battery more than 5v?

 

[Mark Whitney]

Can you tell us more about the headphones. Model, functions, voltage and how are they normally powered?

I think the blue device is a TP4056 1A Li-Ion battery Charging Module. Not bluetooth.

Did you measure any the voltages and are they correct for the headphones?

 

[ng501]

the battery is 3.7v, headphone is a beats studio v2.

the pic i upload is the original set up with the battery and 4056 charging module and 3.5mm jack. it works well with no noise.

However, after i add the module from here
http://www.amazon.com/gp/aw/d/B00ANDHBNS?pc_redir=1414610246&robot_redir=1

it will get a buzzing sound. Again, this module running when i only use the 3.7v battery above and connet it to other speaker.

the problem comes when connect the headphone power, battery, bt module and audio in all together.

some people suggest it is a ground loop problem becoz i use the same power souce for both the bt module and the headphone amp.

thanks for.you guys help!

 

[ng501]

yes the battery voltage is fine and i have no problem when i only run it on the 3.5mm jack...just has problem when its connect to the bt module.,.

 

[ng501]

well i know its crappy, but i forget how to draw circuit diagram....havent used it since high school.......

An externally hosted image should be here but it was not working when we last tested it.

 

[danielwritesbac]

Test: Will the bluetooth module work reasonably outside of that situation?

 

[ng501]

yes it works when i use the same battery and connect it to a headphone dont need power supply with no buzz noise issue

 

[ng501]

thanks daniel btw

 

[Mark Whitney]

Did you try it without the power ground to audio ground connection?
Can you confirm that when you plug the bluetooth device into the charger, the bluetooth device is then only connected to the power supply and not to the battery.
I think the charger is constructed as USB to regulator to battery and that the USB works only as a supply to the charger.

 

[ng501]

no, i connect the charger + battery + bt + headphone parallel...... and put a switch between the battery and bt + headphone

 

[turk 182]

this problem sounds more like it's RF noise rather than a ground loop without a properly designed case and shielding you could be pulling your hair out until you track down the noise source.

 

[danielwritesbac]

Test: Do the headphones work (if you get a plug and) plugged into an ordinary mp3 player?

 

[turk 182]

well after looking at the drawing in the photo you posted i'm wondering why you ran a ground from the supply neg to output audio ground (if the module is properly designed it's output ground should be taken care of internally) this could well be forming a loop!

 

[danielwritesbac]

With ohmmeter, measure between the bluetooth module's audio ground and power ground to see if they're internally connected. They are, probably.
In this case, try using only one ground wire for the bluetooth module, to see if that happens to work.

P.S.
If not, then you can probably try sticking schottky diodes (or even 1n4004) series to power in various locations till you get the buzz stopped. That trick worked on my radio that had to charge and power at the same time. But, I forgot exactly how that was arranged. It was just like: "Oh hey, no more buzz!"