Voltage difference

Discussion in 'General Electronics Chat' started by burtonwisher, Sep 1, 2011.

  1. burtonwisher

    Thread Starter New Member

    Aug 9, 2011
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    I need some assistance with a voltage question I have.

    I have built a circuit that uses a 555 and a 4017 to flash sets of LED's, and it's working perfectly (thanks to previous assistance), powered by a mini battery (MN21 for 12v or 28L for 6v), which I'm using becuase:
    - The 555 needs at least 5 volts
    - The model I'm using it in is too small to accomodate anything bigger, so a 9v PP3 is too big.

    I now want to add another circuit to my model that uses a UM3561 chip to create a siren effect, but the technical spec states that it's maximum voltage is 3.6v, so I'm assuming that I wont be able to run it with my 6v or 12v mini battery.

    However due to the lack of space I need to be able to run both circuits off the same tiny battery. Is there a way that I can do this easily and cheaply? Hopefully by adding just a small number of components for example?

    The schematic of mt UM3561 circuit is attached for clarity.

    Thanks in advance
     
  2. paulktreg

    Distinguished Member

    Jun 2, 2008
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    120
    You could use a few 1N4001 diodes to drop the supply volts to the UM3561?
     
  3. HDAV

    Member

    Aug 21, 2011
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    Last edited: Sep 1, 2011
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    About 5 diodes or one 3V zenor, with 6V battery. What is the drain of the UM3561 at desired volume level?
    A pie in the sky thought: assuming that sound effects are of short duration, cherge a .22F cap to 3V derived from 555- I tried it, 5V to 3V @ 40mA- but alas 555 seemed to run a little hot and I did not get back to it before needing board for something else.
     
  5. iONic

    AAC Fanatic!

    Nov 16, 2007
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    What is the Ah rating of the tiny battery you are using now??
     
  6. burtonwisher

    Thread Starter New Member

    Aug 9, 2011
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    The MN21 (12v) is rated at 33mAh, and the 28L (6v) is rated at 160mAh. I am also open to other battery options if there are any, as long as it's small, i.e. no bigger than about 30mm long by 13mm diameter.

    Thanks
     
  7. iONic

    AAC Fanatic!

    Nov 16, 2007
    1,420
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    Take a look at These Batteries.
    CR123
    They are like mini AA batteries.
     
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