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Posts posted by inferno

  1. ei! help me with circuit.. i want to change the semiconductors...will you please suggest a substitute for this.. tnx!!

    Resistors (all 1/4W 5% carbon film)

    R1,R9      1k (brown, black, red, gold)
    R2,R10,R11   470R (yellow, purple, brown, gold)
    R3,R13      10k (brown, black, orange, gold)
    R4      1M (brown, black, green, gold)
    R5      2k2 (red, red, red, gold)
    R6,R8,R15   220R (red, red, brown, gold)
    R7      10R (brown, black, black, gold)
    R12      560R (green, blue, brown, gold)
    R14      100R (brown, black, brown, gold)
    R16-R23      330R (orange, orange, brown, gold)

    Capacitors (electrolytics 2.5mm spacing, others 5mm)

    C1,C4,C6   100u electrolytic 16V
    C2,C5,C7   220u electrolytic 16V
    C3      100n miniature polyester
    C8,C11      100n ceramic
    C9,C10      22p ceramic


    TR1,TR3,TR4   BC549B npn transistor (or BC547B, 48C etc.)
    TR2      BF244A or B N-channel JFET
    TR5      ZTX313 npn switching transistor
    D1-D3      1N4148 silicon diode
    D4      BAT42 Schottky diode
    REG1      LP2950 5V regulator
    IC1      18-pin DIL socket + PIC16C54 HS/P microcontroller
    DISPLAY1,2   0.56" dual 7-segment LED display, common cathode


    X1      20MHz crystal, HC-49/U case
    S1      miniature pcb vertical slide switch, SPDT
    INPUT      BCN pcb socket
    BATTERY      PP3 battery snap

    4 x rubber feet

    ...... below is the schematic.....


  2. ei!!
    -- is there a short protection circuit here?... when i accidentally short the output terminals, is it ok? what will happen again???.. :)
    -- how to measure the load regulation and line regulation?
    ---can i use one transformer rated 30V 10A to X2 of the circuit?... because i will make dual supply....


  3. ei der!! i have read all the posts.. and they modified the power supply... i have a question, where will i connect RV1? to pin 6 and pin 4 or to the Null?...
    -- just to clarify:
    - is the emitter of Q1 only grounded?
    - has anyone tried the unmodified schematic? because someone said in the first part of the forum the it is working?
    - for what is the changes?.. the TIP31, transfo.. etc...

    ----sorry for the english -----


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