Dc voltage doubler ?

Discussion in 'General Electronics Chat' started by curry87, Oct 5, 2010.

  1. curry87

    Thread Starter Member

    May 30, 2010
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    Is a circuit possible which takes a dc input voltage say 4.5v and increase it to 12v for example without using a transformer,inductor coil or ic for uses in very low <0.1 ma loads like driven the gates on fets for example where just the voltage level not the max available current level matters?
     
  2. bertus

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  3. tom66

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    May 9, 2009
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    FET gates draw more than 0.1mA. They draw it when charging the gate capacitance.

    You can use a 555 timer as a charge pump to get about 7V from 4.5V.

    You could also use a charge pump IC to get your 12V.
     
  4. curry87

    Thread Starter Member

    May 30, 2010
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    Is that pretty much the only option to use a charge pump IC to get more than double the input voltage on the output?

    Using something like a 555 timer voltage doubler how much output current would i be able to draw, enough to light a led ?
     
  5. tom66

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    About a maximum of 10-20mA, so yeah, enough to light an LED. If you don't mind too much ripple, you might be able to get 50mA out.
     
  6. curry87

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    May 30, 2010
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    Are there any other circuits that improve up on the 555 voltage doubler in the way you get more than double the voltage on the output with at least 1ma of current to play with ?
     
  7. bertus

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    Hello,

    There are special voltage doubler chips like the ICL7660.
    See the attached datasheet for more info.

    Bertus
     
  8. curry87

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    May 30, 2010
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    I take its not possible to chain several 555 timer voltage doubler circuits together to gain higher voltage output like batteries in series ?
     
  9. tom66

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    It is, but it is hugely inefficient and needlessly complicated. Each timer will draw ~3mA from your supply. You can get 5mA to 10mA max on the output, think about how little is left to use in your application.
     
  10. bertus

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  11. curry87

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    May 30, 2010
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    Has anyone got a example circuit schematic of two 555 voltage doubler circuits chained up together to provide even higher voltage output than just one ?

    @bertus are you saying i can replace the ac input on the voltage multiplier circuits on the link you provided with a 555 output ?
     
  12. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    How about 14V @ 140μA from one 555 using a 5 X V multiplier. ' started with 1N914's for quadrupler @ 10V, added another stage for 12V; substituted half of diodes with Ge 1N 1N92 & 1N 93's raising output to 14V. Did not have any shottky's.
     
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  13. curry87

    Thread Starter Member

    May 30, 2010
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    Thanks for reply
    Will the 1N4001A series diode work in this application if not please spec similar diode ?
     
  14. Bernard

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    Probably would work but poorly, need to lower frequency, maybe add another stage. 1N92, germanium; shottky: NTE 578, 584, 585, 586. NTE is the only catalog that I have. Sgt. Wookie would probably come up with better numbers.
     
  15. eblc1388

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    Nov 28, 2008
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    Hi Bernard,

    You can get higher voltage output with this modification which could mean one less stage of voltage multiplier can be use.

    [​IMG]
     
  16. Bernard

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    Thanks, absoutly right eblic1388. Add RK44 diode to list & maybe 1N5820, both available from The Electronic Goldmine @ 5 / $1.oo??
     
    Last edited: Oct 12, 2010
  17. Bernard

    AAC Fanatic!

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    1N5820 hit a nerve- I have 10. Vf .23V @ 10mA. Leads .051 in.- too big for socket strip. SN: A10081, 5/ $ 1.00.
     
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