Bluetooth adapter giving noise when powered by same supply

Discussion in 'The Projects Forum' started by SouthernAtHeart, Aug 4, 2012.

  1. SouthernAtHeart

    Thread Starter Active Member

    Jan 2, 2011
    110
    2
    I have a*Belkin F8Z492-P Bluetooth receiver, that I want to use with my 'little buddy' amplifier by amplivox. *This Bluetooth receiver connects to an iPod or other device via Bluetooth, and plugs into the 'line in' on the amplifier and plays... *It works perfectly when I power the Bluetooth off of the included 5 volt wall wart. *But I want it to be portable, and the amplifier runs off 10 (D) batteries. *So I made voltage regulator with a 7805, added a 100uF cap on the Vin side, a 10uF & .1 uF cap on the 5 volt side to make a typical 5 volt supply. *I connect this to the amplifiers battery supply and power the Bluetooth adapter from it, but I get a buzitty buzz as the Bluetooth connects, and then a constant hum there after. *I added a 1000uF cap to the Vin of my new power supply with no affect.
    * *I know there's a lack in circuit quality in this particular amp, but it's very suitable to my needs so I'd like to get it working if possible. *I've included a schematic of the amp which the company sent me. *I've talked to them about a similar issue -- the amp will pick up a buzzing noise when a cell phone goes off nearby. *They said something about the power supply was not designed with shielding for this...
    * *I'm suspecting it's a related problem, but I can live with that one. *If anyone knows how to resolve this Bluetooth adapter issue I'd appreciate help.
    Thanks
    http://www.belkin.com/IWCatProductPage.process?Product_Id=508754


    Here's a link to the schematic for the amplivox amp:
    http://db.tt/vBYWz4Up
     
  2. SouthernAtHeart

    Thread Starter Active Member

    Jan 2, 2011
    110
    2
    Anyone have any thoughts about how to fix this?
     
  3. bertus

    Administrator

    Apr 5, 2008
    15,645
    2,344
    Hello,

    The schematic is to small to read and has no values.

    You can "isolate" the bluetooth adapter using a small resistor (10 - 100 Ohms) in its power line and a capacitors on its power connections( 10 μF and 0.1 μF paralellel).

    Bertus
     
  4. SouthernAtHeart

    Thread Starter Active Member

    Jan 2, 2011
    110
    2
    Thanks. You mean a small resistor in series on the positive, and the cap in parallel (positve to ground connections)?
    Thanks.
    Sorry, about the pdf. I don't know how else to post it. If you download it, then you can zoom way in and read the values on the schematic.
     
  5. andyvp

    New Member

    Nov 5, 2012
    1
    0
    I have the exact same issue. (Very happy to find this disscusion)

    Did you solve the buzz issue?

    Can you post how you went about it?

    Thanks!
     
  6. Guitarans

    New Member

    Dec 28, 2012
    1
    0
    I just bought a cheap bluetooth adaptor from ebay.
    It works fine but i have a noise from it even at 0 or low volume..

    I think i would try to wrap it in foil ans makena mall wire for the antenna.
    Ill let you hear more when im done experimentin.
     
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