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newbie with with a wierd question

Discussion in 'General Electronics Discussion' started by niper99, Aug 30, 2013.

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  1. niper99


    Aug 30, 2013
    Here’s my question!!! I have a travel trailer that at some point someone has installed an after market car radio in it.. the problem lm having is when other lights or devices are turned on in the trailer the radio cuts out just for a second then turns back on... now what's causing this is the AC to DC converter cant maintain a steady 12v + it tends to drop down slightly then pick back up.. So my question is: is there something I could wire inline (like maybe a capacitor)?? Or whatever device that could or would be able to maintian 12v to the radio, even if the voltage was to vary coming from power source??.. No idea if a capacitor is even the right thing just a guess... hopefully this makes some sense...
  2. BlairH


    Dec 3, 2012
    Cold current may be the problem

    Light bulbs have a lower resistance when cold, and the turn on current is higher in the initial fwe milliseconds when the light bulb is activated. Once the bulb reaches temperature, which happens rather quickly, the current drops. If the lights are on the same wiring as the radio, the turn on current may cause enough voltage drop that the radio turns off.

    You may also want to check battery connections, a slight amount of corrosion will add resistance and exacerbate the problem.

    Adding a large capacitor at the input to the radio may help, as the energy in the cap may be able to sustain the radio as the voltage drops. A series forward biased diode before the cap will prevent the cap from giving current to the lights being activated, but will drop the voltage and may need to be fairly heavy if the radio uses a significant amout of power.
    Last edited: Aug 30, 2013
  3. niper99


    Aug 30, 2013
    Thanks for the reply... ya the converter itself should maintain 12v but it an old unit 1986 so I don't want to really replace the unit itself... so what exactly do I need? Diode and a capacitor and how would that be wired? Inline? Does it need to be close to radio?.. And can u give me specs on diode and capacitor if possible? not sure how much power radio uses my guess is 3-7 amps tops!!! Thanks again Doug
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