Recent content by josko

  1. J

    0-30 Vdc Stabilized Power Supply

    I have built this supply long ago, it sits in old AT case, but today I found problem, that on negative (-) supply I am having -40V DC against wall plug ground. It's not problem in general, but if you want to supply something that is for example connected to computer through USB it'll blow the...
  2. J

    0-30 Vdc Stabilized Power Supply

    So it should be voltage between (-) output of supply and P2 (+ input of U3) or am I wrong?
  3. J

    0-30 Vdc Stabilized Power Supply

    Thank you for your answer. I'll explain you my setup: I have separate winding on transformer for 9V supply of fans and panel meters so it is completely separate from measured voltage (voltage meter works OK). I also have voltage divider set up to divide 1.65V to show as 5A = that is 50mV on...
  4. J

    0-30 Vdc Stabilized Power Supply

    Is it much of a problem if I have 0.33Ohm 15W (three parallel 1Ohm 5W) shunt resistors instead of 0.27? I think that it's ok, but I have calculated voltage divider for 0.33Ohm to my 200mV current panel meter that makes 1.65 volt show as 5Amp which I think is OK - 5Amp through 0.33Ohm is R*I...
  5. J

    0-30 Vdc Stabilized Power Supply

    I have one last question (probably). As I understand using only two TIP3055 transistors for 5A power supply is not possible, how many transistors do I need for 5A versions and then what modifications to picmasters circuit do I have to make? I mean I know that I have to add parallel transistor...
  6. J

    0-30 Vdc Stabilized Power Supply

    I have probably broken circuit.. I was trying current sensor and shortened output and now it is not working at all. I mean full rectifier voltage is on output. I see no smoked parts, nothing like that. It just doesnt work. What could possibly gone wrong? I have to note that before this...
  7. J

    0-30 Vdc Stabilized Power Supply

    Thank you. So it is voltage between 3 and GND? I understand that it compares voltage between voltage which is set from reference voltage by P1 pot and voltage on shunt resistor. So I understand that it has the same voltage range on shunt resistor as across shunt resistor? That is what I am...
  8. J

    0-30 Vdc Stabilized Power Supply

    Where should I measure reference voltage that is used for current limiting? And correct me if I am wrong: To get current displayed on 200mV panel meter on which circuit limits I need to just measure shunt resistor and from it's value determine voltage range for reference voltage?
  9. J

    0-30 Vdc Stabilized Power Supply

    Gosh I found it.. I have forgotten to solder one interconnection... stupid me.. it is when you solder at night :D Thank you for your help. And you are right 38 VDC was measured at no load at all I have not tested full load yet, but I have 10Ohm 100W resistor lying around so it's to to do some...
  10. J

    0-30 Vdc Stabilized Power Supply

    I found one difference here and it's that I have -5V DC on C10 on defective circuit and -8.2 on C10 on working one.. but R8 is correct and diodes (D4, D6, D3, D5) seems to be OK too.. I'll try to replace diodes tomorrow, I'll have to go buy some new. Zener voltage on ZD1 is the same on both...
  11. J

    0-30 Vdc Stabilized Power Supply

    Thank you for your answer,  I have 2x 29,7V AC transformer (it is 1200W this makes it 600W for one 29.7V AC on C cores so it doesn't drop under any load, actually when I shorted it once it blow up secondary (and also primary) circuit breakers instead of transformer itself :D). Thank you for...
  12. J

    0-30 Vdc Stabilized Power Supply

    Hi, I have made two modules of picmaster's version, but I have a little issue. First of my two modules is working flawlessly regulating voltage from 0-38V and so the current limiter. But the other visually looking the same (all parts are the same and as well interconnections) is also regulating...
  13. J

    0-30 Vdc Stabilized Power Supply

    redwire: I know that I'll have to redesign that PCB to have wider traces. I wanted some starting point, just didn't want to design PCB if there is one already designed...
  14. J

    0-30 Vdc Stabilized Power Supply

    Ich Will: Is it for this one: http://www.electronics-lab.com/forum/index.php?action=dlattach;topic=7317.0;attach=16065;image And do you have better resolution? Audioguru: What about original PCB... are there many changes from original design?
  15. J

    Re: Valva amps!

    pyrohaz: If you don't need too much power you could build something single-ended from this page  (it is in czech language so I used Google Translator for you): http://translate.google.sk/translate?hl=sk&sl=cs&tl=en&u=http%3A%2F%2Fhlava.webpark.cz%2Fjednocinne.html Especially this...
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