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Things you can do with a current source

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    #1

    Things you can do with a current source

    I've just built myself a 20A current source using a BD139 and two 2N3055s (in the schematic there's only one figured, i use two in parallel for Q2). I feed it with a 9.5Ah SLA battery, just the thing for getting a boatload of amps.

    I built it to use it along with my inductance measuring multimeter to check DC saturation current of inductors for SMPS supplies. But soon i figured there's more things it can be used for.
    • Testing fusing current of wire (for replacing fuses with a piece of wire without tripping the breaker or setting my house on fire)
    • Testing current capability and voltage drop of diodes


    What other uses can you think of?
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    Originally posted by PeteS in CA
    Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
    A working TV? How boring!
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    #2
    Re: Things you can do with a current source

    4-wire resistance testing!
    "Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin slitting throats." - H.L. Mencken

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      #3
      Re: Things you can do with a current source

      Eh, i don't think it's that accurate... It drifts quite a bit.

      Btw, the circuit is only meant for brief operation, it won't do >10A for more than 20-30 seconds. Up to 10A it's alright, higher and the BD139 gets crispy. If you put a beefier transistor in place of the BD139 then the 1N4148 dies. And you can't use a more heavy duty diode because the whole circuit depends on the high voltage drop of the 1N4148.

      There are more elegant ways of making a current source. But for now, this one serves its purpose.
      Originally posted by PeteS in CA
      Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
      A working TV? How boring!

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        #4
        Re: Things you can do with a current source

        i built a t-former 150a @12v(:

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