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  1. xristost

    AC/AC power supply

    One solution which come in my mind is to put a transformer with ratio 1 : 0.46 then at the secondary the voltage will vary from 55VAC to 276VAC. If your AC/DC converter can work with that low voltage - 55VAC, then no switching will be required. But if it can't, then the transformer should be...
  2. xristost

    0-30 Vdc Stabilized Power Supply

    Hi, in my variant I use resistor+ 2 zeners, because voltage is already regulated with LM317, so there will be no voltage drop (if supply voltage is high enough). It's interesting to compare yet another solution for voltage reference - LM317L with resistors 270/1.8k. This will produce 9.58V...
  3. xristost

    0-30V Stabilized Power Supply

    Another solution of this problem is to wire a couple of power diodes in series after the rectifier and smoothing capacitors. Each diode will reduce voltage with ≈0.7VDC.
  4. xristost

    0-30V Stabilized Power Supply

    It's there, in the datasheet: http://www.ti.com/lit/ds/symlink/lm117.pdf (page 21). But it is from 1.2V to 30V In the datasheet have also schematic which goes from 0V (page 20) but without constant current mode. Maybe its possible the first schematic to be modified to go from 0V.
  5. xristost

    0-30 Vdc Stabilized Power Supply

    Yes, yes, whatever . . . You have only words, and I have working power supplies  8)
  6. xristost

    0-30 Vdc Stabilized Power Supply

    It's obvious that you just repeat yourself endlessly. . . 3) I already said that two opamps are one dual opamp, so they have common supply, so IC1A have negative supply voltage. Also read again that part marked in red ind the quote. 2) About the power dissipation you are right, but the number...
  7. xristost

    0-30 Vdc Stabilized Power Supply

    The design in this posting in my blog is the same as the discussed one in this  topic. There are number of small improvements that are mentioned in the posting. The design in this posting is little different and is based on an old schematic published in a Czech electronic magazine. The latest...
  8. xristost

    Power Supplies

    If your power supplies are variable, then you can adjust both of them at 12V and connect them in this way:
  9. xristost

    0-30V Stabilized Power Supply

    Your latest posts are very cryptic, weird and not connected with the subject. Are you OK?
  10. xristost

    variable DC power supply

    Go and see this video: I think that theoretically you can replace output circuitry with switching mode regulator. And if you don't care much for constant current mode, then there are tons of different switching mode regulators like LM2596 or LT1074 for example. They are very efficient, with...
  11. xristost

    variable DC power supply

    Maybe the regulators (LM317L and LM337L) for the opamps can be shared. And for the two channels you must double the C1 capacitor.
  12. xristost

    variable DC power supply

    It's always amaze me how people want more and more amperage and voltage from a variable PS and most of the time they haven't any idea for what purpose they want that. Any way, I would suggest you to get finished module like this...
  13. xristost

    0-30V Stabilized Power Supply

    You must rename all parts to be with same designation in two schematics. It will be much easier to check for mistakes. And about the transistor Q2 in the output - I think it had another purpose - to shut down output voltage quicker when schematic is powered off.
  14. xristost

    0-30 Vdc Stabilized Power Supply

    I didn't find anything like that in the datasheet. There is negative input voltage limit but in this schematic input voltages of IC1A NEVER go below zero, so I don't think there is such danger. And if these opamps (TLE2141 and MC34071) are so common why there is so many question about...
  15. xristost

    0-30 Vdc Stabilized Power Supply

    You are not quite right about IC1A - with IC1B they share common power supply pins and so there is negative voltage -3V. And as I said in my blog both versions are tested and they work very well - I can regulate current limit almost to 5 - 10mA, below that is not possible because of input...
  16. xristost

    0-30 Vdc Stabilized Power Supply

    There is not need for nitrogen neither for huge fan. It's a laboratory power supply which in my book is used for testing some projects, usually for short period of time. Dissipating power will be problem if power supply is used for extended period with low output voltage and high current . When...
  17. xristost

    0-30V Stabilized Power Supply

    1) I deliberately kept Q2 because with it output voltage drop more quickly after power off. 2) R15 is 1k in original schematic and I don't know what will change if I replace it with lower value resistor since everything is working OK. 3) I decided to use only one output transistor, because the...
  18. xristost

    0-30V Stabilized Power Supply

    I finalized my second power supply unit. Now I may combine two voltages up to 60V or use them as dual voltage PS. Pictures, details, schematic and PCB here.
  19. xristost

    0-30V Stabilized Power Supply

    I finished my version of this famous project :) Here how it looks like: http://diyfan.blogspot.com/2012/02/adjustable-lab-power-supply.html You may also download PDF files of the project on that page.
  20. xristost

    0-30V Stabilized Power Supply

    Part of the circuit will not work, because it use AC voltage to make negative supply voltage for U3. But charger will provide only DC voltage.
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