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lighty

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Posts posted by lighty

  1. 0-30V Stabilized Power Supply

    in Projects Q/A

    Posted

    Hi Audioguru

    I seem to be having a problem, I've just finished the second board and while testing, C7 explodes into pieces about a 1 or 2 seconds after I power up, I replaced it and the same thing happened again. The transformer is the same one I use on my other board, so it can't be it.

    any idea where I can start? as I can test without powering it up?

    When I powered it up the 2nd time, I had my meter on the output, and it seemed to sit at about 30V.

    C7 where 10uF 50V electrolytic.

    Thanks

  2. 0-30V Stabilized Power Supply

    in Projects Q/A

    Posted


    With the current-setting pot at minimum, a load of 12mA or more will cause current regulation.
    Maybe C7 leaks as much as 12mA or more because it is connected backwards or because it is defective?

    Opamp U3 is a TLE2141 with a max input offset voltage that is much too low to cause your problem. Maybe U3 is a counterfeit one or is defective?


    Cool, I'll try replacing it. I did notice when I was fiddling with the setting that the output dropped to about -0.3 V.

    I think I will try replace C7 1st then test it again, perhaps the offset is way off?

  5. 0-30V Stabilized Power Supply

    in Projects Q/A

    Posted


    Since your current regulator does not work then U3 or D9 are not working. Maybe D9 is open or is disconnected.
    Maybe you messed up the connections to the current-setting pot or VR3.


    Sorry Audioguru, I think I wasn't clear, the current limiting function is working when adjusting on the POT, but the VR3 "MAX" limit doesn't seem to be working. Since my transformer is only 125va, I need to limit the maximum at 3A prevent any damage.

  6. 0-30V Stabilized Power Supply

    in Projects Q/A

    Posted

    Hi Audioguru

    I've used the TLE2141 opamps.

    I used Redwire's Eagle BRD along with your parts list.

    OK OK,  :-[ Stupid me, I had the wipers from the POTs connected incorrectly, not meant to be in the middle screw... >:(

    But I still have one problem, I can't seem to set the max current limit by means of VR3. I have shorted the output though my meter, and no matter the adjustment of VR3 the current rises over the 4amp mark when I quickly increase and decrease the current POT setting.

    What else could I have messed up with?

  7. 0-30V Stabilized Power Supply

    in Projects Q/A

    Posted

    Hi All

    I'm having a bit of a problem with the adjustments...

    1 - With the current pot set to min the current limit LED lights up, and it has a MIN voltage of about 100mv, can't get it any lower by adjusting RV1.

    2 - I find RV2 makes no changes to anything when adjusting?

    3 - The Voltage pot is LINEAR, but behaves like a LOGs, when adjusting the voltage, anything over say about 10V becomes extremely difficult to dial into, when you get to about 14V the current limiting kicks in, and the POT is SO SO sensitive. Same applies with the current limiting LIMIT adjust (RV3) behaving the same way, changes the limit from about 1A to 2.5A with about 3/4 turn on a 20 turn VR.

    4 -  I also only seem to get a max of 2.5A output.

    Thanks in advance

  11. 0-30V Stabilized Power Supply

    in Projects Q/A

    Posted

    OK, so I ecthed my first double sided boards, not too bad if I say myself!  :)

    Just need to trim and drill. hopefully will have a the components early next week.

    Stupid question, but how do you get the board that nice green colour? is it the protective stray or a differnent type of board?

    post-53956-14279144204276_thumb.jpg

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