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Use AC speakers in Car

Discussion in 'General Electronics Discussion' started by Nauman Muhammad, Oct 26, 2017.

  1. Nauman Muhammad

    Nauman Muhammad

    64
    1
    May 9, 2016
    Hi!

    I have old PC speakers which run on 220v however inside the speakers there is transformer which is converting 220v to 11.9v AC. Now my car has 12v DC Voltage. So how can I convert 12V DC to 12V AC?

    Or is it better to buy 12V DC to 220V AC converter of 0.5Amp and use speaker directly without any modification?

    Speakers used inside each speaker are 3W 4 Ohm each and there are two speakers.
     
    Last edited by a moderator: Oct 26, 2017
  2. davenn

    davenn Moderator

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    1,745
    Sep 5, 2009

    Hi

    you don't have to do any converting, the amplifier in the speaker cabinet housing will be converting from the 220VAC to ~ 11.9V AC as you said but then there will be a power supply
    section that rectifies the AC voltage and converts it to DC

    show sharp and clear photos of the circuit board(s) inside the case so we can help you sort out what is what
     
  3. Nauman Muhammad

    Nauman Muhammad

    64
    1
    May 9, 2016
    Following are the images of speaker: IMG_20171026_114649.jpg IMG_20171026_114728.jpg IMG_20171026_114758.jpg
     
  4. Bluejets

    Bluejets

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    698
    Oct 5, 2014
    Supply across the large electrolytic cap from what I can see.
    Keep polarity correct ........

    I doubt it will put out much in the way of power though, probably hardly be able to hear it above road noise.
     
  5. kellys_eye

    kellys_eye

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    Jun 25, 2010
    Just cut the blue wires and apply 12V DC there - polarity is irrelevant.
     
    CDRIVE likes this.
  6. Nauman Muhammad

    Nauman Muhammad

    64
    1
    May 9, 2016
    Thanks.. Actually its winter and I need a low sound, not much.. I shall be grateful is you can show in diagram as I am very begineer :)
     
  7. Nauman Muhammad

    Nauman Muhammad

    64
    1
    May 9, 2016
    I have 12v DC battery. Shall I try without removing blue wires from circuit?
     
  8. kellys_eye

    kellys_eye

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    Jun 25, 2010
    NO!

    You MUST cut the wires from the transformer (the blue ones). Cut them in the middle and apply 12V straight to them. If you want to revert to AC power then just bare the ends and twist them back together where they came from (use insulating tape too).

    Note that volume may well be lower than original as the 12V DC is going to be lower than rectified 12V AC. But there's no other 'simple' way to achieve what you want to do so no harm in trying.
     
  9. kellys_eye

    kellys_eye

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    Jun 25, 2010
    Oh, and don't forget to FUSE the 12V supply (2A fuse should be ok)
     
  10. Nauman Muhammad

    Nauman Muhammad

    64
    1
    May 9, 2016
    Thank you. Is there any way to get full sound i.e by altering circuit? As the sound is already not much even with AC.

    Further, will socket of car cigarette lighter be fine to use? I have 12v cigarette lighter plug which already have a fuse.
     
  11. kellys_eye

    kellys_eye

    4,284
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    Jun 25, 2010
    Cigarette socket is ideal place to take the supply from.

    Other than using a DC-to-AC inverter you can increase the 12V DC supply using a 'boost converter' board - readily available from many cheap Chinese outlets (via eBay etc). This can be adjusted to give the required 15-16VDC that the board will probably operate from normally. I suspect you won't see very much difference in output between 12V and 15V though.

    If I was to obtain a boost board from 'China' I'd probably also purchase a 12V amplifier for around the same 'low' price instead.
     
  12. Nauman Muhammad

    Nauman Muhammad

    64
    1
    May 9, 2016
    I used 12V 1.3Amp power supply but it did not work, and no power came with DC 12V connecting to blue wires. I cut the wires coming from transformer to circuit and connected circuit with 12v DC but it did not work. I already have one extra car CD player which is totally in working condition.. Can I use this with these speakers? If yes then how?
     
    Last edited: Oct 26, 2017
  13. Nauman Muhammad

    Nauman Muhammad

    64
    1
    May 9, 2016
    These are the images of CD Player. IMG_20171026_151251_242.JPG IMG_20171026_151318_648.JPG
     
  14. kellys_eye

    kellys_eye

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    1,145
    Jun 25, 2010
    Did the speakers work originally? If yes then there's an issue with your 12V 1.3A supply. If you connected the 12V without cutting the blue wires you've probably blown the fuse in the 12V supply.

    The CD player you show is likely to have a relatively high output power and may well damage any low powered speaker you connect.
     
  15. Nauman Muhammad

    Nauman Muhammad

    64
    1
    May 9, 2016
    Yup speakers are working on AC. With my multimeter power supply is giving me voltage of 13.84v as it a battery charger. I cut the wire and made AC totally separate. It did not work. I reconnected blue wires and speakers are working on AC. Power supply is also giving 12VDC.
     
  16. kellys_eye

    kellys_eye

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    Jun 25, 2010
    Did you connect the 12V DC to the blue wires going to the amplifier board?
     
  17. Nauman Muhammad

    Nauman Muhammad

    64
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    May 9, 2016
    Yes..
     
  18. kellys_eye

    kellys_eye

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    Jun 25, 2010
    You're doing something wrong somewhere..... there's no way it can work on AC and NOT work on DC.

    Measure the voltage across the smoothing capacitor (DC) with the AC supply connected and then with the DC connected. You should measure 'DC' (of some value) in both examples. What do you get?
     
  19. Audioguru

    Audioguru

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    576
    Sep 24, 2016
    That is what small cheap speakers do. No bass, probably no highs and not much loudness.
    If your car battery is fully charged at 13.8V then the rectifiers will reduce it and feed about 12VDC to the circuit. But the 11.9VAC has a peak voltage of 1.414 times higher than 11.9V at 16.8V and the rectifiers reduce it to 15V which is 25% more than the 12V.

    Powered from only 12VDC the very cheap and small amplifier IC probably produces a max output of 8VAC which produces only 2W into the tiny 4 ohm speaker. Ordinary car radios produce 14W in each speaker.

    I agree that the Kenwood disk changer will blow up the cheap tiny speakers.
     
  20. Nauman Muhammad

    Nauman Muhammad

    64
    1
    May 9, 2016
    Eureka! It worked with batteries.. Don't know why its not working with battery charger, however charger is giving 13.84VDC. Is there anything linked with Amps as battery charger is of 1.3Amp?

    One more question, can I use 19v power supply, an old laptop adopter?
     
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