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  1. redwire

    Single Chip Temperature Data Logger

    Have you thought about using something like this  http://learn.adafruit.com/adafruit-data-logger-shield ? You would need to get a Arduino  to plug the shield  into, but the Arduino could be used for numerous other projects.   The listed project will require a programmer to flash the microchip...
  2. redwire

    0-30V Stabilized Power Supply

    sonycman,    Good luck.    Did you check out http://www.electronics-lab.com/projects/test/007/index.html ?  It will give you a starting point for a MCU output display.  The hex file provided  is for a Atmega8 chip so don't purchase a Atmega88 chip. 
  3. redwire

    0-30V Stabilized Power Supply

    sonycman,  U3 requires a voltage between 0 and 1.5V (for 3A output) and U2 requires a voltage between 0 and 11.2V to adjust the output voltage.  If you are using a microcontroller, couldn't  you delete U1, and U3 and feed a DAC signal to U2 of 0-5 V to control voltage (Yes you will need to...
  4. redwire

    0-30V Stabilized Power Supply

    denci,   This is a picture of a MJ11016 (upper left hand corner of picture) I was using to test my new smd board http://www.electronics-lab.com/forum/index.php?action=dlattach;topic=7317.0;attach=19559 At this time I was using a brake light bulb  (about 2.5 A).   The previous 5A test was done...
  5. redwire

    0-30V Stabilized Power Supply

    On my unit with an output of 30.0V,  U2 pin 6 has an output of 30.07, pin 2 11.46V,  Pin 3 = 11.44. No load If U2, pin 6 has an output of 13.8V, pin 2 = 5.02,  pin 3 =5.00V R12 is 55.6K , R11 with pot = 34.5 KOhms;  amplification = 1+ 55.6/34.5 = 2.61.  This is very close to  measured...
  6. redwire

    0-30V Stabilized Power Supply

    Hi DrinkH2O4,    I don't know if anyone is going to try to match up parts on the board layout provided, to see what Picmaster changed from the design being discussed on this thread.  It would certainly be easier with the sketch layout but you may need to pick a design and either ask Picmaster...
  7. redwire

    Hello

    Hello michaellot,  Welcome to the board.  Check out the blog and projects for some interesting builds
  8. redwire

    0-30V Stabilized Power Supply

    Then why not eliminate D8, U1, R5, R6, and R4  and replace with one T0-92 that can handle a 40V input voltage that would get power from the 10V zener?  These voltage regulators are pretty indestructible with thermal, voltage and current cutoff features. L7812AC.pdf
  9. redwire

    0-30V Stabilized Power Supply

    What I was referring to was L7812 type.  These have poor voltage regulation ? 
  10. redwire

    0-30V Stabilized Power Supply

    audioguru,  Why is U1 and the associated negative and positive feedback necessary to output 11.2 V, used instead of a simple voltage regulator in the 11-12 volt range?
  11. redwire

    0-30 Vdc Stabilized Power Supply

    Was your goal to provide a easy to build, basic PS or will this be part of a more comprehensive design that may include current control?  I would have a concern about having the output shorted.
  12. redwire

    0-30 Vdc Stabilized Power Supply

  13. redwire

    0-30 Vdc Stabilized Power Supply

    I ran a test with  a 0.47 10W resistor at about 1.2 V.  1.2/0.47 = 2.6 A .  I only have it attached to a 100VA, 28V transformer so I guess it was about pegged out because the current control led did not come on.  After a while, the heat sink on the one output transistor was very hot to the...
  14. redwire

    0-30 Vdc Stabilized Power Supply

    liquibyte,  I had the boards made by a commercial pcb shop.  On my other PS,  I have (2) 2N5886G's on a aluminum heatsink about 4" x 7" x 1" with a small computer fan blowing across it.  It is amazing how effective a small amount of air blowing over the heat sink is.  I would not recommend...
  15. redwire

    0-30 Vdc Stabilized Power Supply

    One more picture of the rig operating
  16. redwire

    0-30 Vdc Stabilized Power Supply

    audioguru,      Finally got everything tied together for a quick test of the smd board.  I ran a 3156 taillight bulb (about 2 A) for around 4 minutes.  No heat sink on the bridge diode or BD139.    The heat sink on the MJ11016 output transistor was quite warm,  the bridge rectifier diode was...
  17. redwire

    0-30 Vdc Stabilized Power Supply

    On a MOT the secondary windings are very small wires with many windings  because it steps up the voltage  to thousands of volts.  Remove these very small wires and rewind these.    This should be consistent with many of the tutorials.  The problem with using standard wire is that the insulation...
  18. redwire

    0-30 Vdc Stabilized Power Supply

    liquibyte ,  I'm searching for some pictures of the final build but I haven't found any yet.  I took a MOT from a large microwave (1100w) that I found at the dump. I removed only the secondary windings because the primary seemed large enough to handle the load.  I purchased a thick copper...
  19. redwire

    0-30 Vdc Stabilized Power Supply

    U2 Drives the output transistors.    With a minimum gain of 1,000 for the MJ11016, a 3A output will require a  3/1000 = 3 milliamp current from the BD139.  The BD139 has a minimum gain of about 40, so 3milliamps /40=  nothing. The C-E saturation voltage for the MJ11016  is 200mA at 20Amps,  so...
  20. redwire

    0-30 Vdc Stabilized Power Supply

    I'm working on a smd version of this board with the TLE2141ID chip.  The only thru hole components are the BD139, bridge rectifier, and R7.  I plan to use a MJ11016,  a darlington power transistor with a minimum gain of 1,000 in lieu of the  2N3055.  Sure you may loose 0.7 volts on the output...
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