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  1. audioguru2

    0-30V Stabilized Power Supply

    You should learn how to post schematics here instead of over there. Your new post is the same with its parts spread out too much so everything is small. When enlarged then it is too blurry. It has no contrast. I can't see ANYTHING on your schematic. Can you see anything?
  2. audioguru2

    0-30V Stabilized Power Supply

    I copied your schematic from PhotoBucket because it is too small here. Even at PhotoBucket it is too small because its parts are spread apart too much. I tried to enlarge it but then it was too blurry. Its very low contrast makes everything look faint. I increased the contrast and it looks much...
  3. audioguru2

    0-30V Stabilized Power Supply

    No, because it is completely different. The TLE2141 and MC34071 opamps were selected because: 1) Their max allowed supply voltage is 44V and they do not need a negative supply voltage. The TL081 max allowed supply voltage is only 36V and they need a huge negative supply voltage. 2) The inputs of...
  4. audioguru2

    Blank screen when I try to reply

    I recently received two e-mail notifications to replies to a topic I participate in but clicking on the link shows a blank screen. Here is one link: http://www.electronics-lab.com/forum/index.php?topic=7317.new;topicseen#new When I find the topic in Recent Posts the same blank screen occurs...
  5. audioguru2

    topic for thesis

    Why do you ask? We don't know what you studied. We don't know what country you are in. I guess you attended most classes and I assume your teacher was good. Maybe not?
  6. audioguru2

    0-30V Stabilized Power Supply

    I don't know why there are two threads with (almost) the same name. I answered your other post. Please do not post the same questions twice.
  7. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Srecenvid, The 5A version has only a few changes from the 3A version: 1) More powerful transformer, 28VAC/200VA or 30VAC/212VA. 2) Medium size heatsink for the 10A rectifier bridge module. 3) R7 changed to 0.27 ohms/10W. 4) Three output transistors on a huge heatsink with fan and a 0.33...
  8. audioguru2

    0-30V Stabilized Power Supply

    I don't know why you can't buy 12000uF but since you can only get 10000uf then try one to see if the project needs more uF.
  9. audioguru2

    0-30V Stabilized Power Supply

    I selected 12000uF because it works best and is a common value. 10000uF will be almost the same. How many uF is in your "10000uf" capacitor when its tolerance is plus or minus 20%? It might be as low as only 8000uF which might cause ripple when the output is 30V at 3A.
  10. audioguru2

    0-30V Stabilized Power Supply

    There have been a few pcb designs for the latest circuit. Yours is another one but I am sorry mthat I don't have time to check it.
  11. audioguru2

    0-30V Stabilized Power Supply

    Yes you found the latest parts list and schematic. The transformer can be 28VAC/4.2A or 30VAC/4.2A. A higher current rating is fine.
  12. audioguru2

    0-30V Stabilized Power Supply

    A little 25V/3A transformer will overheat when it tries to supply more than 75VA. If the output voltage of the project is 25VDC at a current of 3A then the max (b]load(/b) power is 75VA. But the rectifier bridge uses an additional power of 6W max and the R7 current-sensing resistor uses 4.2W...
  13. audioguru2

    0-30V Stabilized Power Supply

    This project is powered from an AC transformer, not DC.
  14. audioguru2

    0-30V Stabilized Power Supply

    Maybe. It uses ONE ordinary 28V or 30V, 50Hz or 60Hz power transformer. Of course not, it uses an AC power transformer, not a 40V battery. Why don't you power this project from a power transformer like everybody else?
  15. audioguru2

    0-30V Stabilized Power Supply

    The existing negative -1.3V supply for the opamp U3 is simple, cheap, supplies plenty of current and is fairly well regulated. The iCL7660 needs to have a resistor feeding a 9.1V zener diode to power it plus two capacitors. Its output current is low and is not regulated. Its output voltage must...
  16. audioguru2

    0-30V Stabilized Power Supply

    1) The original project has opamps rated for an absolute maximum supply of 36V operating at 40V. 2) Its transformer, rectifier diodes, driver transistor, output transistor and many resistors get too hot and will probably fail soon. It cannot produce 30V at 3A. So we fixed it to work properly...
  17. audioguru2

    0-30V Stabilized Power Supply

    Since you do not show where you are then we cannot recommend parts. The max total dissipation from both output transistors is 117W. They should have their chips  below their max temperature of 200 degrees C. If the ambient is 30 degrees C then the total allowed allowed temperature rise is 175...
  18. audioguru2

    0-30 Vdc Stabilized Power Supply

    The very old CA3140 is completly different to a modern TLE2141 opamp: 1) Its maximum allowed supply voltage is too low. 2) It is very noisy. 3) Its datasheet talks about it oscillating.
  19. audioguru2

    Transformer coupled transistor amplifier

    Solid state amplifiers have extremely low distortion at any power level becaue their open-loop gain is high and a lot of negative feedback reduces the gain to a useable amount and also reduces the distortion. The negative feedback makes the output have an extremely low impedance (0.04 ohms or...
  20. audioguru2

    Transformer coupled transistor amplifier

    Where have you been for 56 years?? Amplifiers have not used push-pull and output transformers since 1955 when Philips showed a portable amplifier with them using germanium transistors. Your circuit has no negative feedback to reduce distortion so it will sound horrible. Modern amplifiers use...
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