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  1. redwire

    0-30V Stabilized Power Supply

    Some accessories I'm working on.  The display On issue when building the display is programming the chip.  I'm building a board with smd components that uses the 32u4 breakout board from Adafruit.  It can be programmed with a usb connector and does not need a special programmer.  While simply...
  2. redwire

    0-30V Stabilized Power Supply

    picotrain ,  The actual board layout has not changed since I posted the pictures in the first post.  One or two part values have changed.  I had several boards made if you would like to purchase one/two.  I suspect it would significantly cheaper than getting 3 boards made. Send me a PM if you...
  3. redwire

    0-30V Stabilized Power Supply

    gizmo322,   try http://www.electronics-lab.com/projects/mcu/008/index.html.  There is  an AVR version out there http://www.electronics-lab.com/projects/test/007/. I'm working on a version that uses an Adafruit 32u4 breakout board and uses a usb cable to program, eliminating any expensive...
  4. redwire

    0-30 Vdc Stabilized Power Supply

    What about Farnell/element14/Newark?  very common part
  5. redwire

    0-30V Stabilized Power Supply

    After adding the 10V Zener, I don't think R22 was  adjusted on the parts list.  Shouldn't R22 be approximately 1.5K. 
  6. redwire

    I need some advice on a project I'm working on please

    So you basically need a chip with random number generator to randomly flash the lights twice. 
  7. redwire

    help

    Are you serious?
  8. redwire

    [need help] Temperature alarm

    Try an Arduino with a breakout board for the power supply, temperature sensor, and led (strobe).  Do you know anything about soldering or programming?
  9. redwire

    0-30V Stabilized Power Supply

    Yes,  Some of the benefits: 1.  Develop skills in making pcbs, and using software such as Eagle. 2.  Learn troubleshooting 3.  Utilizing a design (as revised) that is probably the best available 4.  Ability to ensure quality parts are used 5.  Satisfaction and pride in successfuly...
  10. redwire

    0-30V Stabilized Power Supply

    denci,  You should not need to change any parts to use the 3 MJ series transistors
  11. redwire

    0-30V Stabilized Power Supply

    denci,  none
  12. redwire

    0-30V Stabilized Power Supply

    The MJ15003 is a good power transistor.      The thermal Resistance, junction to case is about the lowest you can get but getting that to transfer to the heat sink is more difficult.  The power derating of 1.43 W/C is high if you are running hot but when you start at 250W you've got plently of ...
  13. redwire

    URGENT help with my PIC16F628A project

    Did  you try the updated version at the bottom of the page?    Considering the code is already compliled  (hex code provided) most of the big issues should be resolved.    I am not familiar with PIC but with AVR's the fuse settings may need to be checked. 
  14. redwire

    0-30V Stabilized Power Supply

    U2 is not tied to the negative rail in my PS, what I meant to say is that the PS output will go to 0V (with no load )on the one that has the 5.6 zener.    That one is driven by a rewound MOT that puts out about 44V resulting in about 50V output. It is certainly outside the TLE's range but has...
  15. redwire

    0-30V Stabilized Power Supply

    Audioguru,  not sure if I'm understand how the absolute value of U2 is above 44V with a 28V transformer.  U2 is not tied to the negative rail. 
  16. redwire

    0-30V Stabilized Power Supply

    red baron,  1.  can you do a test with two 0.33 ohms in parallel on R7 to see if the voltage drops. 2.  Do you have the 10V zener in backwards 3.  Q3 could be bad 4  I noticed that when the 10V zener was added, I changed R22 to 1.2K  I can't remember if it was becasue I have 2 leds in...
  17. redwire

    0-30V Stabilized Power Supply

    red baron, Many builders have experienced the same.   This is common when the negative rail is only -1.3V.    The PS I built with the 5.6 v zener instead of the two diodes in series allows the voltage to be set to zero, whereas the PS I built with -1.3 rail will only go down to about 0.3 volts...
  18. redwire

    0-30V Stabilized Power Supply

    red baron,  Outstanding build!  Very tidy and professional looking-Congratulations.  How about a photo of the front face and sides?  Where did you get the case from?
  19. redwire

    0-30V Stabilized Power Supply

    Audioguru,  Also note that the 10V, 1W Zener is listed as D12 on the parts list but on the schematic D12 is an led indicator for the current control.  If you make the changes I'll  post the revised parts list on the first thread.
  20. redwire

    0-30V Stabilized Power Supply

    raresvintea,  check out http://www.electronics-lab.com/forum/index.php?topic=7317.msg1009204#msg1009204 or search for "inversion"  it will answer your questions about the Q1 and TL081. I don't understand the concern that the new op-amps cost more.  They are about $1 more ($3 total) for the...
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