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Portable Speaker Project

Discussion in 'General Electronics Discussion' started by Jai B, Oct 29, 2015.

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  1. Jai B

    Jai B

    3
    0
    Oct 29, 2015
    Hiya, I am new to this forum and just needed some help on things I know very little about.

    I am building myself a new portable speaker system to take out with me etc.

    I am using a box which I have designed and created for the system itself.
    I am using a car radio as the amp from Ebay (A cheap one around £20, it will do the job).
    And a 12V motorcycle battery with 10amps capacity.

    One issue I need to get around is recharging the battery while it is in it's enclosure and finding a circuit or device which will tell me when it's fully charged and what percentage it is at! So a female plug in for the power outside the enclosure!

    ANY TIPS OR HELP WOULD BE AMAZING. This is a cheap product but I just wanna making a cool system! :)
     
  2. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    First question is, why did you not buy an amp from Ebay instead of an entire car radio? It would have been cheaper, smaller, lighter, and if you got one of the class D ones, used a lot less power, probably more than doubling your battery life.

    All you need to do to charge the battery is put a connector to the two battery terminals and a mating connector hooked up to a smart charger you could also get on EBay.

    Here, for example:

    http://www.ebay.com/itm/Hi-Fi-PAM86...073023?hash=item4aeb86ffff:g:2kwAAOSwrklVeAkh

    Bob
     
  3. Jai B

    Jai B

    3
    0
    Oct 29, 2015
    Hiya Bob! Thanks for the reply.

    That was my initial idea! There is a good circuit with good reviews with 2X50w output for £17! But, most of these only have Bluetooth.

    I thought it made more sense to buy a radio for around the same price as it has all of the controls, plus usb charging for phone an Aux etc!

    The product you linked is not powerful enough for the speakers I want to use as it has a 20w max output!

    Could you give me any advice to linking a little screen device which would tell me how much of the battery is left.

    Also would it let me use while the battery is charging?

    I am very new to this. I just want to make nice loud with great sound quality speaker that lasts long ish. I have 2X50w speakers from my old car at the ready which proved suffice. I also want to get tweeters so car radios already have all of this integrated in them!

    Thank you for your swift and helpful response!
     
  4. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    10Ah capacity at 12V is 120Wh, 40 Watts with a normal amp (not class D) will probably use 100W and therefore last about 1 hour on batteries. If you really want this to be good I would:

    1. Use LiIon batteries, which have much more capacity for the same weight.
    2. Find very efficient speakers, which will probably put out the same sound level on 1/4 of the power.
    3. Use a class D amp which will use 1/2 the power of a linear amp.

    But, if you are trying to build this on the cheap from parts you have and 1 hour is enough play time, then go for it.


    Bob
     
  5. Jai B

    Jai B

    3
    0
    Oct 29, 2015
    Oh really? Wow I didn't expect that! I thought a motorbike battery would last hours on end with a car radio as car radios in car don't just last an hour, even when powering the electrics in a car, speakers etc! I'm shocked.

    I can't really get less power speakers as I want excellent sound quality and not tinny etc with brilliant bass response.

    I really thought a battery like this: http://www.ebay.co.uk/itm/GENUINE-Y...hash=item1e5da04d84:m:mGToqKaTUHBJg6AM_9wcoog

    Thought it would last ages with a car radio and pair of 50w speakers?

    Thanks!
     
  6. GPG

    GPG

    452
    66
    Sep 18, 2015
    There are a few other factors to take into account. The peak to average value of the program material. (10-16dB) this works in your favour. The total capacity of the battery is not available,and it may damage the battery if exceeded. Cars carry a battery with 5x or more capacity. See if you can find a deep cycle battery.
     
    Last edited: Oct 31, 2015
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