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  1. audioguru2

    0-30V Stabilized Power Supply

    That is only one of hundreds of parts where the voltage is too low. What about the other hundreds of parts where the voltage is too low?
  2. audioguru2

    0-30V Stabilized Power Supply

    The resistors and voltage drops all must be re-calculated to use a much lower supply voltage.
  3. audioguru2

    0-30V Stabilized Power Supply

    A laptop charger has only 19V. This project uses 40V.
  4. audioguru2

    0-30V Stabilized Power Supply

    A 38VAC transformer without a load might be 39.5VAC. When rectified and filtered the raw DC is 54.4VDC. But the U2 opamp has an absolute max allowed supply of 44V so you have a lot of power to throw away.
  5. audioguru2

    lm7805 question

    The datasheet recommends 0.22uF input and 0.1uf output ceramic disc capacitors. The LM7805 might oscillate with 10uF or 100uF electrolytic capacitors. Of course if the input was rectified AC then a huge main filter capacitor is needed in addition to the 0.22uF ceramic capacitor.
  6. audioguru2

    0-30V Stabilized Power Supply

    I am in Canada where nearly all electric things use 120V/60Hz but high power electric things like the electric stove, air conditioner and electric clothes dryer use 240V. So I use 120V transformers. In Brasil you probably use 110V transformers. VA is how much power passes through the...
  7. audioguru2

    Function Generator Simulation (Need Help)

    What a mess!
  8. audioguru2

    0-30V Stabilized Power Supply

    Two little MJE3055's are not good enough for this project. Maybe if you use four of them. The output voltage of U3 goes only as high as about +14V so its collector voltage can be reduced by the zener diode. But the output of U2 must go much higher than the maximum output voltage of +30V. U2 and...
  9. audioguru2

    0-30V Stabilized Power Supply

    Please translate "caught the tompa" into English.
  10. audioguru2

    Function Generator Simulation (Need Help)

    The power supply does not use a BD136 or BD140 PNP transistor. Instead it uses a BD139 NPN transistor but a BD137 NPN transistor will work fine.
  11. audioguru2

    Parts Identification Help Needed

    Capacitors C101 to C104 are connected parallel to each diode in the bridge rectifier to reduce rectifier buzz on an amplifier or radio circuit. The parts list will have values of the inductors.
  12. audioguru2

    Function Generator Simulation (Need Help)

    It is not a generator, it is a 30V max power supply. If the voltage is set to 30V, the max current regulation is set to 1.5A or more and it has a 20 ohm load then the current is 30V/20 ohms= 1.5A. The output voltage cannot exceed 30V. You set the voltage up to 30V then you set the maximum output...
  13. audioguru2

    Function Generator Simulation (Need Help)

    The maximum amount of output current is adjusted with the current regulation pot. When the output current tries to exceed the setting of the current regulation pot then the output voltage is reduced until the current is what was set. Example: Set the current regulation pot for a max current of...
  14. audioguru2

    Function Generator Simulation (Need Help)

    The circuit works perfectly and is very reliable.
  15. audioguru2

    0-30V Stabilized Power Supply

    Why are you asking about a multimeter?
  16. audioguru2

    0-30V Stabilized Power Supply

    Redwire's and my versions are almost the same. We both added the calibration trimpots at the same time without seeing the other one so the trimpots are in different locations. I think there is a pcb designed by Redwire but I didn't design one. There are also a few other pcb designs.
  17. audioguru2

    Function Generator Simulation (Need Help)

    The latest circuit for the 0V-30V, 3A power supply uses MC34071 or TLE2141 opamps that are very common and inexpensive in North America and Europe. Go to www.farnell.com and click on the flag of your country. Then order them online or go to their office to get them.
  18. audioguru2

    0-30 Vdc Stabilized Power Supply

    Measuring the setting of current regulation is complicated because the voltage at the current-setting pot is the 11.2V voltage reference divided plus the voltage across R7.
  19. audioguru2

    Function Generator Simulation (Need Help)

    Sorry. I stopped using the very old LM723 voltage regulator driver about 30 years ago. There are many good circuits in its datasheet.
  20. audioguru2

    0-30 Vdc Stabilized Power Supply

    It does not matter because you adjust the calibration resistor for your meter so it reads correctly. Your panel meter reads wrong because it is not calibrated or because it is powered from the same supply that it is measuring. Your multimeter has its own shunt resistor that is in series with the...
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