mask project

Discussion in 'The Projects Forum' started by keithg, May 21, 2012.

  1. keithg

    Thread Starter Active Member

    Jan 17, 2009
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    I am an artist making a series of masks made of Fisher Price toys. These include a board with sound, LEDs, and motors. I want to use four or five with each mask from a single 12v battery and one speaker. I have made the 386 amplifier but have failed to make a successful power source after hours and hours of experimenting and searching web resources. The 7812 regulator is fine but the toy circuit/amp circuit are not. I am trying to power the 386 amplifier circuit and the toy from two of the trimmers. When using the batteries native to the toy the circuit runs as expected directly to the amplifier circuit. Any advise would be appreciated.
     
  2. milesguidon

    New Member

    Dec 4, 2010
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    Do you know the required voltages of each of the circuits you are trying to power?
     
  3. wayneh

    Expert

    Sep 9, 2010
    12,155
    3,061
    It would be very helpful if you could sketch a schematic or even block diagram of what you are doing.
     
  4. keithg

    Thread Starter Active Member

    Jan 17, 2009
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    I assume the voltage can be known simply by the battery case of each toy. Sorry, a schematic is beyond my skill level. Here is a rough drawing that may help. Thanks.
     
  5. milesguidon

    New Member

    Dec 4, 2010
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  6. keithg

    Thread Starter Active Member

    Jan 17, 2009
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    I will have five of these toys to power. May I simply tap off the same line with 5 of the regulators you describe for each one?
     
  7. milesguidon

    New Member

    Dec 4, 2010
    11
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    You only need one regulator to provide the 8V or the 3V--unless you're drawing a lot of current. The current that the linear regulator can provide has to be *greater* than the sum of the currents required by everything you put on the output of the regulator.

    The regulators I posted can only provide 100mA and 50mA. You might search on digikey for Linear regulators (LDO) that provide ~1A or 500mA, so you can use many toys on one regulator.
     
  8. keithg

    Thread Starter Active Member

    Jan 17, 2009
    40
    0
    Thanks for the help. I will search for the regulator.
     
  9. keithg

    Thread Starter Active Member

    Jan 17, 2009
    40
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    This buck booster has four outlets. Would this work?
     
  10. keithg

    Thread Starter Active Member

    Jan 17, 2009
    40
    0
    Sorry, here is the link.
     
  11. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    Keithg,

    The part you linked runs almost $5 and will require several more parts, probably bringing you close to $10 altogether. Of course, this may well be more efficient than a linear regulator meaning your 12V battery may last longer.

    The datasheet for the 386 claims it can accept 12VDC maximum. Can you safely power the 386 circuit with 12V directly? You could connect a 1N4001/2/7/etc. diode in series with the positive power lead of the 386 circuit. This will result in roughly a 0.7V drop to the 386, so providing 12V will actually only allow the 386 to get about 11.3VDC, giving you a little safety and protecting the 386 circuit if the battery leads are somehow connected in reverse by accident.

    For the 3V supply, a quick search turns up this: http://www.digikey.com/product-detail/en/MCP1827S-3002E/AB/MCP1827S-3002E/AB-ND/1223080. This will provide 1.5A minimum, although honestly you don't want to pull more than about half of the rated current from a linear regulator of this type. You may need a heat sink depending on the current draw. You can also use a LM317 adjustable regulator, just be sure the resistors selected to set the output voltage have a high enough wattage rating.

    Do you have a multimeter? Could you put the batteries of one of the toys into a separate battery holder? Then you can check the current draw of the toy by putting your meter in current mode (I can explain how to do this if you can tell us your meter model number) and placing it in series with one of the battery leads which will get connected back to the toy. Turn on every light, motor, etc. on the toy at the same time to find the maximum current draw. Multiply that number by the total number of toys you plan to use and you'll have your current draw. Multiply that number by 2 to get the minimum current rating you need on a regulator.

    Could you provide a link or model number of the Fisher Price toys you are using? We may be able to approximate or I may have something similar in my son's toys to take these measurements and give you an idea.

    Lastly, what kind of 12VDC battery are you planning to use? If you can provide a model number, we can also come up with a rough operating time.
     
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