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Simple Electronics Problem...

Discussion in 'Electronic Basics' started by WhoCares, Jan 9, 2005.

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  1. WhoCares

    WhoCares Guest

    All I wanted to do was make a Sony DVD remote run on a power adapter
    instead of batteries (for a business application). The remote uses 3v
    from 2 AA batteries so i got a 3vdc 500ma power adapter from Radio
    Shack connected with a mini phone jack. Well some of the buttons
    worked but some either didn't or were erratic. I check the voltage on
    the power adapter and it was 3.8v so i took it back and got a 3vdc
    1000ma adapter that checked at 3.1v so i tried that one and same
    problem. Put the batteries back in and it works fine.

    I've done this on other remotes the same way with no problems but this
    one seems to be picky. I imagine the power isn't clean enuff but i
    don't have a scope to check. Can i just put a electrocap across the
    power? or something like that....

    Thanks :)
     

  2. Think you've done some overkill. A remote controller is hardly a load for
    the batteries until you press a button. Then it wil take some mA to power
    the IR-LED. Modern power adapters are small SMPSs that often do not very
    well without load. An electrolytic capacitor of let's say 10-100uF mounted
    near the remote controll may be a good remedy. You can also try some dummy
    load using a resistor of 150Ohm parallel to the cap.

    petrus bitbyter
     
  3. WhoCares

    WhoCares Guest



    I tried 47uf cap and 151omh resistor both parallel to the supply and
    still the same... was that what you meant? both parallel?
     
  4. WhoCares

    WhoCares Guest

    Sounds worth a try... what values do you suggest and in series or
    parallel?
     
  5. Jamie

    Jamie Guest

    its more than likely the Wallwort is inducing some R.F. noise on its
    wires and is getting in the remotes electronics.
    try using a couple of chokes and by-pass caps in both teh + & -
    leads at the battery clip end.
     
  6. Jamie

    Jamie Guest

    something around 1 mh choke and 1 nf give or take a abit.
     
  7. That's what I meant and I'm surprised it didn't work. Did you place them on
    the remotes side? Next you can try is adding a 1-5nF ceramic parallel to the
    elco. Just to short hf-ripple. Then try a small resistor (1-4.7Ohm) or a
    choke (1mH) in series with the power line. Place this one(s) near the
    capacitors on the side of the supply. A series diode may also work but it
    will lower the voltage on the remote with about 0.6V (unless you use a
    Schottky).

    petrus bitbyter
     
  8. WhoCares explained :
    take a good look at the battery compartment. Is there 2 or 3 wires
    going from it to the board?. if 3 then the board uses 2 voltages and a
    converter will not work
     
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