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  1. Sallala1

    0-30 Vdc Stabilized Power Supply

    1n5402 protect the 2n3055 transistors, but how to protect U2? In a switched off PSU, current can be flown from the output througt D10->R15 and into U2 output. Isn't it? What about to use a Shotky diode? It have only 0,3V drop. Or you can limit the maximum voltage with a trimmer potentiometer...
  2. Sallala1

    0-30 Vdc Stabilized Power Supply

    Dear Bongo! Why do you place the 1n5402 diode to the top of the 2n3055 transistors? To save the transistors, when the PSU is off, and there is a voltage connected to the output? (A charged big capacitor, orr accumlators for eaxmple) Maybe it isn't enough. As Audioguru says in an earlyer post...
  3. Sallala1

    0-30 Vdc Stabilized Power Supply

    Audioguru: Something wrong in my workplace's internet access. I can't see any pictures attached to the forum at work. At home everíthing fine  ??? But it's doesn't matter. I'm sorry: T3=Q3 (In my country, Transistor=T) Huhh, I checked it, but I don't remember exactly. It wasn't...
  4. Sallala1

    0-30 Vdc Stabilized Power Supply

    I have got another problem: - My fuse (5A) at the secunder side of the transformer glowed. - T3 went out - Fuse at the output (5A) desn't damaged I used a 1,5-3Ohm load at 3-4V at 3A. (Cutting polystirol foam with hot wire) I use only one 2n3055 at this time, with heatsink and a big fan. This...
  5. Sallala1

    0-30 Vdc Stabilized Power Supply

    Audioguru: My browser (Firefox) can show PNG files. I don't know, what was the problem. Now I can see the images twice... Thank you anyway! I will buy a high current shotky diode, and will build into the pcb or inside to the supply's case. OK, I understand, what you tell about the batteries.
  6. Sallala1

    0-30 Vdc Stabilized Power Supply

    Audioguru! I can't see your pictures attached!
  7. Sallala1

    0-30 Vdc Stabilized Power Supply

    While the voltage keeps climbing, your batteryes doesn't fully charged. See it's technical manual! When the voltage stops climbing, and start decrease about a few millivolts, at this point your batteryes fully charged. The newer -dV chargers stops charging at this point too.
  8. Sallala1

    0-30 Vdc Stabilized Power Supply

    Hey, it's neccesarry for everyone isn't it? For example, if I put a circuit with a bigger puffer condensator on it's input, that can damage the power supply if the mains off. Not? I remember, on some three terminal stabilizer IC's manufacturer suggest a bypass diode between the leg 1 and 3. So...
  9. Sallala1

    0-30 Vdc Stabilized Power Supply

    If I use a 4,8V battery pack for example, and set the voltage to 5,2V the curent can't remain constant. A fully charged 4,8V NiMH batterypack's voltage about 5,2V. No voltage difference between the supply and the battery, -> no current isn't it? I use several type of batteries, I need the...
  10. Sallala1

    0-30 Vdc Stabilized Power Supply

    Audioguru: thank you for the quick answers again! - Yes, I'm thought to use a series diode too! (But I'm sure now because you confirm) - I think, timer doesn't neccesarry, only once. 1. Just charge the battery pack, with full voltage and adjusted current according to the battery. 2. Measure...
  11. Sallala1

    0-30 Vdc Stabilized Power Supply

    Can I list all of the posts on one page in this topic somehow?
  12. Sallala1

    0-30 Vdc Stabilized Power Supply

    Ok, then Q1 emitter go back to 0V. I will make the modification. Just a new hole  :-X I made a summarize about the project on my homepage: http://sala.sallala.hu/elektronika/szab_dc_tapegyseg/tapegyseg.html This time only for my language, (Hungarian) I will update this. And then what about the...
  13. Sallala1

    0-30 Vdc Stabilized Power Supply

    Great tipp Alun! Thank you, I will try this. But you know, to print something to a leser printer, you must to draw it with a computer. ;-)
  14. Sallala1

    0-30 Vdc Stabilized Power Supply

    As I read in the topic: Q1 for pull down the output voltage, if you decrease the voltage adjust potentiometer. The current flows throught R7, Q1's emitter voltage increased, and T1 won't conduct->U2 can drive T2 If thers no current flow througth R7, then Q1's emiter go down, it's base...
  15. Sallala1

    0-30 Vdc Stabilized Power Supply

    Twentyone century. Nevermind! I plan and made my PCB-s with my hand :-) 1. plan the connections on a papper 2. put the paper to the pcb, and sign the holes with a sharp prod 3. clean the brass plate well 4. now, you can see the place of holes on the brass plate, draw the pcb with water resist...
  16. Sallala1

    0-30 Vdc Stabilized Power Supply

    T1's emitter connected to the input voltage's null point. This is wrong! T1's emitter must to connect to the output's 0V, otherwise it doesn't make it's job.
  17. Sallala1

    0-30 Vdc Stabilized Power Supply

    Spagbol: Oh, I missed. You need to modify the Q1's emitter, not Q2. Now I will correct my post. (at Q1, you know, what to modify?)
  18. Sallala1

    0-30 Vdc Stabilized Power Supply

    Ok, I will unsoldier the potentiometers, and measure they. My R4 is 1k, as according to the modified part list. I promised the pcb plans. Here they are: My finished PCB's picture. My modified soldier side plan My modified pcb side My finished circuit, and my transformator. This time...
  19. Sallala1

    0-30 Vdc Stabilized Power Supply

    I measured the DC voltage again. It's 42VDC on C1. (I measured the 46V before I put the IC's into the panel. Maybe this makes the difference?) My pots are 10K. (as the label says) U1 output is just 10,56V for me. (I sed BZX 5v6 as D8) U(D8) is 5,25V Something wrong with my reference? I'am...
  20. Sallala1

    0-30 Vdc Stabilized Power Supply

    Thank you for the reply Audioguru! I have a very poor English knowledge. I mean: split = not conduct  ::) Of yourse, I use a metal case 2n3055, as the picture that you attached. Spagbol: thank you, I know that, and use a heatshink with a fan. But it' true, not a good resistor value for the...
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