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Unsymmetrical Dual Rail power supply

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by Llamarama, Jan 13, 2018.

  1. Llamarama

    Llamarama Member

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    Hello everyone, I want to make a dual rail power supply, but with unsymmetrical outputs. I need +13v and -10v. I will need to supply around 100mA, so that rules out a voltage divider. I found a circuit in the Datasheet for an L165 Power op amp that looks like it would be ideal, but i'm having trouble sourcing these, so I'd rather avoid them. Does anyone have other circuits I could try? Thanks, Mike :)
     
  2. Les Jones

    Les Jones Well-Known Member

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    Use a 15 = 0 - 15 vollt secondary transformer with a bridge rectifier and capacitors. Regulate the positive rail using an LM317 and regulate the negative rail using an LM7910 (Or an LM337) 15 - 0 - 15 is a little on the high side for voltage but the next standard one down (12 - 0 - 12)would be too low.

    Les.
     
  3. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    1000 words:
    upload_2018-1-13_11-37-16.png
     
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  4. dave

    Dave New Member

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  5. Llamarama

    Llamarama Member

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    Thanks for the quick replies, I forgot to mention, this has to run off a DC supply! Sorry guys!
     
  6. audioguru

    audioguru Well-Known Member Most Helpful Member

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    You did not say why you need a negative supply. I would use a 23V supply and bias the opamps or transistors at +10V and use input and output coupling capacitors.
     
  7. Les Jones

    Les Jones Well-Known Member

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    You have now forgotten to give us information on the DC power supply.

    Les.
     
  8. tomizett

    tomizett Active Member

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    Yep. How many volts is the DC supply? Also, do you need any particular relationship between the incoming DC supply and your +13V, -10V outputs - for instance:
    is (+supply in) connected to (+13V out) or
    is (-supply in) connected to (-10V out) or even
    is (-supply in) connected to (ground out).

    I wonder if the L165 is discontinued? It used to be pretty standard. A quick look on RS turns up the LT1010, which is in the same category, but there might be cheaper options.
     
  9. Llamarama

    Llamarama Member

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    Sorry for the lack of details, the perils of writing a post in between jobs :)

    I need +13v and -10v so I can run a Fluke 8050A I got with a dead mains transformer off batteries, which would also be more useful for me rather than to replace the transformer.

    I have a stash of step up DC-DC modules I can use to step whatever battery voltage I have up to 23v rail to rail.

    I think the L165 is long out of production, but leafing through the datasheet for the LT1010, there's a very similar circuit so I think i'll order one of them and breadboard it. Thanks :)
     
  10. Les Jones

    Les Jones Well-Known Member

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  11. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    12V battery step up to +13 and a isolated converter to make -10V.
    The isolated output(+) goes to ground and output(-) is -10V
     
  12. tomizett

    tomizett Active Member

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    It might be advisable to go with a linear post-regulator or some extra LC filtering, to keep switching noise out of the meter. I don't know how sensitive it would be to this - maybe others can comment?
     
  13. Colin

    Colin Active Member

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    Just put 4 or 5 diodes in the -10v line to reduce the voltage.
    Then go out and buy the CRAY computer to scrounge the diodes.
     

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