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Automotive 12-volt convert to dual 1.5 volt output

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  • Automotive 12-volt convert to dual 1.5 volt output

    Here's the deal. I have two auxiliary inputs on my car radio. The signal is very weak, so I bought two cheap headphone amplifiers (Fiio E3) to boost the input signal (XM radio receiver and cell phone/tablet/mp3 player). The headphone amps work great, and make the input sound great and full; already tested with no issues.

    Problem is, the amps are powered by a AAA battery, so 1.5 volts each. They only turn on when the output of the amp is connected, and last about 20 hours on a charge when constantly on. So instead of replacing the battery every day (I plan to have these buried inside the dash of the car, so the output will always be connected), I want to make some kind of voltage divider/regulator to power both headphone amps when the car ignition is on. So in theory I would have to drop 14.5-ish (engine running volts) down to two 1.5 volt outputs to drive each headphone amp.

    Any ideas on how to accomplish this? Thanks in advance!


  • #2
    There are a number of ways to do this but the simplest might be to simply go to Radio Shack or some other place and get a cigarette adapter for your power source or to find a similar amp that will run off a car.

    Otherwise the PROPER way to do it is to build a voltage regulation circuit that can supply the amperage you need and work with a car voltage input.

    But I would be very surprised if you couldn't find an automotive based device to do the same thing you are doing now. If I am understanding you the signal from your devices isn't amplified enough to feed the stereo a good signal.


    • #3
      1.5V outputs may be difficult to find; 3V is difficult enough.

      For 1.5V I'd suggest an LM317 adjustable regulator, though if the current draw is low (which it should be), maybe a simple Zener regulator - maybe with 2 or 3 normal diodes instead of a Zener.

      If it's a rechargeable AAA it'll be 1.2V but if it can also handle a normal AAA it'll handle 1.5V and maybe 1.8V (3 x 0.6V diodes).


      • #4
        Why reinvent the wheel?
        link to my CTS-V project:


        • #5
          That's a 5V output, not 1.5V.

          peder - why dual 1.5V? Can't you parallel the loads?


          • #6
            I could have sworn the thing was 1.5 volt, my bad

            Here is a correct one:

            link to my CTS-V project:



            • #7
              Originally posted by heavymetals View Post
              I could have sworn the thing was 1.5 volt, my bad
              LOL - you probably did my and others common bad - saw the "1.5A" but read it as "1.5V".

              But you did find a suitable 1.5 Volter. As I said, they tend to be rarer (many start at 3V). Well done (not meaning to sound patronising - I'm just reinforcing my usual POV!).