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  1. redwire

    New Power Supply

    I used thru hole parts for this trial board.  I don't see any reason why smd parts wouldn't work just fine.  The only parts that get warm are the bridge diode, resistor for power on led and the .22 ohm 5W non inductive resistor when pushing a heavy load.  I built the board to also fit a 10W...
  2. redwire

    New Power Supply

    Good News.  I built the subject PS with the following changes: 1.  Used 10,000uf  main cap instead of 4,700 uf 2. Used TLE 2141 op amps with caps similar to Project Power supply 3.  Deleted funky zener/Fet/Resistors reference voltage an used a 12V linear regulator as reference voltage for...
  3. redwire

    0-30V 0-3A Latest Data Discussion

    Yes,  I agree the proposed fix would likely give rid of a lots of parts and simplify the board.  When you add the two addtional transistors, is Q3 still needed or will the lower transistor connect to the led instead?  One thing I am curious about is how low the output will go with the...
  4. redwire

    0-30V Stabilized Power Supply

    Why do you use 30V instead of the collector voltage of approx 40V (with a 28V transformer) when computing the power?
  5. redwire

    Programmer

    KINGTIGER,  it appears that you don't want to use an Arduino (where only a usb cable is needed to program the chip) but rather have a ATMEGA8 in mind -perhaps because of a project you found uses one?  Or, you want to do direct programming.  Have you considered the 324u breakout boards from...
  6. redwire

    Programmer

    I agree 100% with Electropepper.  Buy a commmercial programmer or build one from a kit.  You will find support in either case if you have questions.  The one shown looks old and who knows if it supports the chips you will eventually want to program.  Do you plan to use AVRStudio for writing...
  7. redwire

    0-30V Stabilized Power Supply

    These actually look pretty good to me but I'm no expert.
  8. redwire

    0-30V Stabilized Power Supply

    Here is U2 at 12V at startup with 0.5 amp load.  Second try was a bit shaky as it was just holding against pin 7 while trying to plug in the transformer.
  9. redwire

    0-30V Stabilized Power Supply

    Here are views for U1  at 12V  0.5 amp load
  10. redwire

    0-30V Stabilized Power Supply

    No, I don't have any beefy N or PFETs.  I'll probably order some in a week.
  11. redwire

    0-30V Stabilized Power Supply

    I did some testing with the TIP141 and 5 amp load and nearly burned up the TIP because I didn't have a decent heat sink.  I put the Tip on medium sized heat sink and noticed the temperature rise to about 125 C which was hotter than anything else on the board, even the output transistor heat...
  12. redwire

    0-30V Stabilized Power Supply

    No, let me do some thinking on what I could use to load it up.  I do have a headlamp that is 12V and about 4.5A.    Perhaps I can find a small electric heater.
  13. redwire

    0-30V Stabilized Power Supply

    A 34Ah battery?  Was it for a riding lawn mower?  If you are going to use the power supply at its limits for long periods of time you may want to consider upgrading to a couple of 2N5886 or MJ11016 output transistors mounted on a large heat sink with a small fan blowing across it.  A  2N3055...
  14. redwire

    0-30V Stabilized Power Supply

    Yes, that's it.  What are you using to create your pics, Eagle?
  15. redwire

    0-30V Stabilized Power Supply

    Ok I've gotten something that seems to be working fairly well  I have a 39k connect to the high side, then a 2.2k connected to the 39k then a 47uf connected between the 2.2k and ground.    Then I have 4K7 resistor connected at the voltage divider between the 39K and 2.2k.  The other end of the...
  16. redwire

    0-30V Stabilized Power Supply

    Attached is a picture of the charge on the main cap vs output to a 12.4 V setting under a 0.5 Amp load.  The turn on is a flatter curve and slower but  I don't know what I saw yesterday when I thought I had a 1 sec delay.  I must have misread the time period.  I agree that the turn on after...
  17. redwire

    0-30V Stabilized Power Supply

    After some experimenting, I'm not thrilled with the soft start results.  I don't know if adding all those parts are worth the benefit.
  18. redwire

    New Power Supply

    Concur,  I suggested some caps earlier in the thread.
  19. redwire

    0-30V Stabilized Power Supply

    Yes that's it.    I want to try with a low value resistor and no resistor where you show the 18K reisistor to see if the delay remains approximately the same.  For the test I am using a 10,000uf main cap.  Glad you got the part.
  20. redwire

    New Power Supply

    Do you have a suggestion on a different output transistor or opamp? EDIT:  This combination exists on the other PS project but I don't recall anyone mentioning a problem with the tLE2141 getting fried.
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