Independent sources from a 9 V

Discussion in 'General Electronics Chat' started by Rogare, Apr 7, 2012.

  1. Rogare

    Thread Starter Member

    Mar 9, 2012
    78
    0
    Hello, I'm looking to get two independent voltage sources from a single 9 V battery. This would be for the case where two stages of a circuit can't have the same source, but the whole thing needs to run off one battery. Any ideas on this would be terrific. Thanks!
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,014
    3,234
    If they can't share the same ground point, then you will need an input-to-output isolated DC-DC converter, such as a flyback type, that contains a transformer.

    Edit: How much current is required by each circuit?
     
  3. jtrent

    New Member

    Mar 11, 2012
    26
    4
    "Two stages of the sames circuit", sounds to me like one supply source would handle this. You did say it's the same circuit. Right? Maybe if we could see the circuit it could be helpful.
     
  4. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    You could always use battery adapters, the kind you would use for D cells or whatever.

    If you are wanting to start with a 9VDC source then other ways of doing it would prevail.
     
  5. PaulEE

    Member

    Dec 23, 2011
    423
    32
    I recently came up with, what I thought, was a neat solution to this problem.

    A friend required a 3v battery to produce +5v (can you guess why!?).

    I hooked a MAX232 chip up and used the charge-pumped +/- 9v. Worked like a charm - and they're pretty popular. You can also use a decent amount of current before you run into problems.

    Have fun

    Edit: Before someone quotes the Vsupply(min) on the max232 datasheet - I tested it and it worked down to around +2v; surprisingly.
     
  6. WBahn

    Moderator

    Mar 31, 2012
    17,747
    4,796
    Abusing parts like this is okay for hobbyist type projects -- hell, it's part of the fun!

    Just never lose sight of the fact that it worked on the one you tested. It might work on 99.9% or it might only work on 0.1% and you just got lucky.

    Having said that, most parts will work within performance spec for quite a bit outside of their recommended operating conditions -- it's the only way the manufacturers can guard against process and environmental variations. On the other hand, high-volume commodity parts are highly optimized, which in part means that they have a target for how many will not meet spec outside the recommended operating conditions and the circuit is designed not to outperform that goal by very much.
     
  7. Rogare

    Thread Starter Member

    Mar 9, 2012
    78
    0
    Thanks for all the ideas! I'm going to take a closer look at the design and see what might work best.
     
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