Recent content by redwire

  1. redwire

    0-30V Stabilized Power Supply

    Dave,   Can you provide a sketch showing  the transistor layout between U1 and U3, as well as your modified the power supply to U1?
  2. redwire

    0-30 Vdc Stabilized Power Supply

    I'm planning to build (another) power supply with Q1 to see if it clamps down the output to prevent spikes when the power is shut down.   I plan on using 7.5K and 240 ohm divider.  With power on, the base of the transistor will be -0.03V.  When the negative rail collapses, the base of Q1 will be...
  3. redwire

    0-30 Vdc Stabilized Power Supply

    I have a question about the sizing of the resistor divider for Q1 on the revised schematic.   Currently it is listed as 12K and 160 Ohms.  When the negative rail (-1.3V) is operating, the base voltage on Q1 will be approx. -0.7V assuming a Vdc of 39.6 on the top rail.   When the power is...
  4. redwire

    New Power Supply II

    Thanks for the reply.    I guess there is no getting around not having a negative charge pump with this type of design.  I'm curious to see how this guy gets around the problem.  Considering he is using a .1 ohm resistor, the theoretical load would be substantial before there would be...
  5. redwire

    New Power Supply II

    Here is the sketch with the diode on Pin 3 to compensate for the diode drop on the current op amp.  Would this work?
  6. redwire

    New Power Supply II

    Yep, your right.  could you add another diode on Pin 3 of the Voltage op amp after  the other diode leading to the current op amp.  This way the voltage set for 0 V output is actually  0.7 on the line leading to the non inverting pin.  Then the current op amp would only need to bring pin 3 ...
  7. redwire

    New Power Supply II

    Yes I did forget to show the diode from pin 3 on the voltage Opamp to prevent positive voltage  from the current op amp.    The op amp (TLE2141) can handle 0-44V and sink up to 80ma.    I estimate there will be  no more than 8ma to sink on the current opamp and about 3ma output on the voltage op...
  8. redwire

    New Power Supply II

    How about this redesign ? Circuit_II.pdf
  9. redwire

    New Power Supply II

    Another question:  Is the 100K resistor base resistor for Q2 (2n2222 voltage control transistor)  really necessary?
  10. redwire

    New Power Supply II

    Would using a voltage divider from the output of the Opamp to the 2N2222 allow a significantly lower base resistor and reduce the phase shift?  Would a different transistor also help?
  11. redwire

    New Power Supply II

    This is not a revision of the Power supply with 163 pages.  This is a different design  based on the original circuit here.  Which was posted on Youtube here    Although I changed some values I did not add any transistors or reconfigure the basic circuit design but I did add some caps for the...
  12. redwire

    New Power Supply II

    But I didn't add another driver transistor unless you are referring to the use of the MJ11016 darlington output transistor.  I did try the circuit with a 2N5668 and it had the same output problems.  The original design used a 100uf cap at the output. Initially I thought this was too high and...
  13. redwire

    New Power Supply II

    Would adding a resistor to the base of Q1 (BD140) and to the base of the power transistor be a solution?  What about changing to complimenary transistor set up (BD139) with a lower gain rather than the 2N2222 which has a much higher gain?
  14. redwire

    New Power Supply II

    The other thread seems to be corrupted or locked so I will continue here Although I had many wires and jumpers the PS seemed to work well and testing seemed good until i shorted the board and burned some traces.  Happy with the design, I had 3 new boards made and populated 2 of them. ...
  15. redwire

    New Power Supply

    Looking for suggestions.    I built the board as shown in the above post with quite a few wires and jumpers and things seemed to work very well.  I then had 3 boards made.  I populated 2 of them.  Strange things happend on the new boards.  With no load the output would spike about once every...
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