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  1. audioguru2

    0-30V Stabilized Power Supply

    I am not a SIR and I have never built this power supply. I simply corrected its problems and made it more reliable. A few people have posted their pcb design for it.
  2. audioguru2

    0-30 Vdc Stabilized Power Supply

    "TB4" is not on my parts list and not on my schematic. Where did you see it? A shunt resistor is used in a current-meter.
  3. audioguru2

    0-30V Stabilized Power Supply

    Page 55 of this thread has a reply from me where I attached the latest parts list and schematic for this corrected project for the millionth time. Since it was 7 months ago then I will attach them here again:
  4. audioguru2

    0-30 Vdc Stabilized Power Supply

    Yes. Your new circuit is correct.
  5. audioguru2

    LM358 - Dual Low Power Operational Amplifier

    This Chinese SPAM was also posted on another site. The LM158 IS NOT new, it is about 39 years old. It is noisy (hiss), has crossover diistortion and has trouble above only 2kHz. Its max supply voltage is only 32V. I replace it with an MC33172 that has the same very low supply current and...
  6. audioguru2

    0-30V Stabilized Power Supply

    This website does not have "stickies" like most other electronics chat sites. This website does not allow you to key in a page number so you must go back only 2 pages at a time which takes a long time to get to page 55.
  7. audioguru2

    0-30 Vdc Stabilized Power Supply

    No. The positive input (ground) to the negative regulator is shorted to its positive output (ground). The negative regulator needs a transformer winding, bridge rectifier and filter capacitor that are completely separate from the circuit of the positive regulator. 
  8. audioguru2

    0-30 Vdc Stabilized Power Supply

    You can easily make a negative supply from a second circuit that is completely separate from the first positive circuit (also a separate transformer winding) if you use its positive output as the 0V and use its 0V as the negative output voltage.
  9. audioguru2

    0-30 Vdc Stabilized Power Supply

    The latest parts list for the improved circuit shows real 2N3055 transistors in a metal case, not little TIP3055 transistors that might melt. The transistors have only a positive supply, no negative supply. Opamp U3 has a negative supply. Maybe you are looking at the original project that is...
  10. audioguru2

    Transistor OverHeaating

    I could not find a datasheet for the very old 2SB511 PNP Japanese transistor, only a few spec's. Its max continuous collector current is 1.5A so your 3A relay overloads it. -5V on the base? -12V on the collector? Then you are using it as an emitter-follower with a voltage of 6V across it times...
  11. audioguru2

    0-30V Stabilized Power Supply

    The uA741C opamp is 43 years old. Its max supply is only 36V but the supply for U1 and U2 in this fixed project is 40VDC when it has no load and is higher if the mains voltage is a little high so it will fail soon. Its inputs must be 3V above its negative supply so your -2.7V negative supply is...
  12. audioguru2

    0-30V Stabilized Power Supply

    Which opamp did you use?
  13. audioguru2

    0-30V Stabilized Power Supply

    Unlike most opamps, the MC34071 and the TLE2141 have inputs that work as low as the negative supply which can be ground in some circuits. So U1 and U2 do not use a negaive supply and the negative supply for U3 is only -1.3V. Their max allowed supply is 44V. No. When the current control is set to...
  14. audioguru2

    0-30V Stabilized Power Supply

    The MC33171 is low power so its idling power supply current is 1/9th the current of an MC34071 (I use them in low power battery-powered circuits) and its output high current is too low for this project at 1/9th as much as from an MC34071.
  15. audioguru2

    0-30V Stabilized Power Supply

    Their datasheet show that thew xxxxx1 is a single opamp, the xxxxx2 is a dual opamp and the xxxxx4 is a quad opamp. The datasdheet shows that the MC33xxxx has a very wide spec'd ambient temperature range for NASA but the MC34xxxxx has a tempreature range that is reasonable on earth. Guess why...
  16. audioguru2

    0-30V Stabilized Power Supply

    No. They are completely different. Why don't you look at their datasheets? The CD4071 is a Cmos digital quad 2-input OR gate. It has 14 pins. An MC34071 is a single linear bipolar opamp with some special features that ordinary opamps do not have. It has 8 pins. A TLE2141 is also an opamp with...
  17. audioguru2

    0-30V Stabilized Power Supply

    Hi J Rhodes, The BD139 powers the load if the two 2N3055 output transistors are shorted, are wired wrong or their 0.33 ohm emitter resistors have a value much too high. Then it will burn. If the 2N3055 output transistors have minimum gain then the max current in the BD139 is 75mA and is 38mA...
  18. audioguru2

    transisor sl100

    On the other website you were told that it is available in India with different names. I found its datasheet. It is in an old metal case and can dissipate 800mW. Its max current is 500mA. Its max voltage is 50V. Its gain can be low or high. Post the circuit it is used in so we can see if any...
  19. audioguru2

    0-30V Stabilized Power Supply

    Maybe the current regulation is not working and you overloaded this power supply circuit. Then the output transistors and/or driver transistor and/or opamp are shorted. That is normal because you disconnected the negative feedback from the output to pin 2 so the voltage on pin 2 is much too low...
  20. audioguru2

    0-30V Stabilized Power Supply

    Morpheous, If your transformer produces an unregulated 46VDC without a load, then it must be producing only 41VDC with a load which is horrible voltage regulation. Or maybe the value of the main filter capacitor is too low. Maybe your transistors were damaged when you had them connected backwards.
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