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noworries2004

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Posts posted by noworries2004

  1. 0-30V Stabilized Power Supply

    in Projects Q/A

    Posted

    Fantastic news got newmc34071 yesterday and the circuit works perfectly,
    Found problem in other circuit, pin 4 of U3 was 20V, 187ohms between pin 7 and 4 so chip blown,

    Working perfectly now,
    Thanks a million for your help everyone especially Audioguru and Redwire.

  4. 0-30V Stabilized Power Supply

    in Projects Q/A

    Posted

    Ok starting again with a fresh PCB.
    All components have correct value double checked all resistors with ohm meter.
    How ever i am missing 34071 Opamps. The only available opamps are 741 opamps. Is it ok to use these instead?

    Also i dont have .47ohm (R7) resistos. Will it be ok to leave this out and forget about the current limiting. Is it ok to put in a piece of wire instead?

    Also any more suggestions.
    My problem with the last PCB was that i had it on aero board and when i first plugged it in a couple of components smoked. (R7 and U2). Can i test this circuit with a dc power supply first before i plug in the transformer, bridge rectifier.


    Thanks for all your help.

    Regards

  6. 0-30V Stabilized Power Supply

    in Projects Q/A

    Posted

    Just changed the wiper on the 2 pots,
    prob still there but U2 not heating up as fast
    Quick question, Think R7 (0.47ohm ) is blown, disconnected it from the circuit and it is measuring 26Kohms,
    dont have a replacement, is there any other resistor that i could put in.

    I am measuring all my voltages with the neg lead of voltmeter at the - sign between r7 and c7 on the schematic is this correct is this ground ?

    Cheers

  13. 0-30V Stabilized Power Supply

    in Projects Q/A

    Posted

    Finally connected up m ypower supply unfortunately it is not working,
    Measuring from Ground, using a 29.4 volt transformer 4 A.
    I am getting an input to R1 of 41V, how ever i am also getting this 41V at the output,
    Measuring voltage pot, i am getting  a range from 1.1V up to 10.86V.
    I am reading 1.082 V across R5+R6, 0.541 across R5.

    Some how the input voltage is going straight through to the output?
    Has anyone got any ideas or suggestions. Email me back for further information.
    I am using th PCB recieved from Red wire so that is definetly ok.

    Cheers
    Really need some help guys

  15. 0-30V Stabilized Power Supply

    in Projects Q/A

    Posted

    HI
    I am currently constructing the updated version of this power supply,
    I have a fwe questions about this power supply.
    Q1 ; What happens when current limiting kicks in, does the output voltage drop or does it stay steady. If current limiting is then does this mean that the power supply is a constant current source rather than power supply.

    Q2 ; What is the output regualation of my power supply. Input transformer is 31.6 V AC.

    Also what is the rated load of this power supply.

    Thanks for your time especially redwire and audioguru.

    Cheers

  17. 0-30 Vdc Stabilized Power Supply

    in Projects Q/A

    Posted

    Hi i have setup the up to date circuirt schematic, I am using a 31.61VAc transformer. However my U2 just went up in smoke, I have everything wired correctly as far as i know. Did anyone have similar problem, Also i think my R7 smoked too. Any one got any ideas on what maybe causing the sizzling effect.
    Cheers

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