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  1. redwire

    0-30V Stabilized Power Supply

    Hold off on populating the soft start.  I started testing last night and the arrangement and values will likely need to be tweaked.    As drawn, the PS kicked on at the same time as the main cap -no good.  I then rearranged the set up by connecting the 47uf cap directly to ground and used  a...
  2. redwire

    New Power Supply

    Yep, your right about the component values.
  3. redwire

    New Power Supply

    I also sketched this a few days ago up but your Eagle skills are much better.  Please check on the following items: 1. The LM358N has a range of 3V-32V which is out side of the needed operating range of the voltage sense amplifier.  Suggest using a TLE2141. 2.  The current sense amplifier has...
  4. redwire

    0-30V Stabilized Power Supply

    Luisitou,  liquibyte has posted a parts list with part numbers to assist you in ordering.  Unless you are using parts from your lab.
  5. redwire

    0-30V Stabilized Power Supply

    No, I have been focused on the shut down issues.  I'm confident a soft start can take care of the inititial startup spike.  I just sent you a TIP 141 today.  It will likely be next week before you get it.  It is estimated that at full output (3 amps), the TIP will be using about 3.6 watts. ...
  6. redwire

    0-30V Stabilized Power Supply

    From memory I think it looks like the inverse of the first one.  Spike right before it ramps up.
  7. redwire

    0-30V Stabilized Power Supply

    Yes it is with Q1, R13, R14 and D10.  The picture is when I unplug the transformer and the voltage is decreasing.
  8. redwire

    0-30V Stabilized Power Supply

    I installed the diode between the emitter and base of the output transistor. It seems to have helped but I still seem to be getting a spike right (first picture)  before the voltage drops when I pull the plug on the transformer.  The second picture is an expanded view of the first picture.  I...
  9. redwire

    0-30V Stabilized Power Supply

    I don't know how you could see a transient spike without a trigger and screen capture.  It happens so fast.  I often have to change the trigger voltage,  type of edge trigger, and capture rate because the first shot doesn't always  catch it.    If the event happens early, the scope will capture...
  10. redwire

    0-30V Stabilized Power Supply

    liquibyte,  did you have the Q1 clamp transistor installed?  Did you have D10 and R15 installed? Have you tested at 12V with the current setting at about half way? On a couple of my tests I have also noticed what appears to be a one point spike both postive and negative early in the the...
  11. redwire

    0-30V Stabilized Power Supply

    I was using a darlington MJ11016 power transistor with long leads (18") so I hooked up a 2n5886 with shorter leads and didn't notice any elimination of spikes. I ordered a 0.22ohm current sense resistor but in the mean time  I used a jumper across the wirewound sense resistor.  While it kills...
  12. redwire

    0-30V Stabilized Power Supply

    I tried at 3V with the current at max and I got a flat line with no load.    I tried with 12V and got a ringing.  I am using a darlington power transistor so tomorrow I want to swap to a non darlington transistor. I moved the emitter ground to the transformer side of R7 but it did not solve...
  13. redwire

    0-30V Stabilized Power Supply

    I populated a new board and set up the clamp down transistor as shown on the original project but  using the new resistor values.  I tested and when I remove the negative voltage to the base it will turn off.    I then setup the scope on the output set at 12V connected to a tail light bulb and...
  14. redwire

    0-30V Stabilized Power Supply

    Pretty interesting,  can't wait for Part 3.  It doesn't use negative rail  or a clamp down transistor so it is much simpler.  Lets see how well it works 
  15. redwire

    0-30V Stabilized Power Supply

    How about a soft start such as: document2014-09-09-094358.pdf
  16. redwire

    0-30V Stabilized Power Supply

    Hey liquibyte,  if you need more boards, I've got one or two populated through hole variants without the linear regulator and film cap if you run out of space to place jumpers on the smd variant.  ;D
  17. redwire

    0-30V Stabilized Power Supply

    I proclaimed victory too early.  I found the spike on the posted board with certain settings on the scope.  I replaced U1 with a linear regulator and with the scope on the same settins I did not see a spike ,probably because it was happening at a significantly lower frequency.    I failed do...
  18. redwire

    0-30V Stabilized Power Supply

    I'll second the comment about RV1 having no measureable effect on the circuit. 
  19. redwire

    0-30V Stabilized Power Supply

    Thanks for the feedback. 
  20. redwire

    0-30V Stabilized Power Supply

    Hi EmbeddedCom,  I built a smd version of this PS and it seemed to work fine, except I finally bought an oscillosope and started testing things and noticed a ripple at start up and shut down.  I always wanted to try a linear regulator instead of U1 so i built another smd board.  I didn't not...
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