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  1. audioguru2

    0-30V Stabilized Power Supply

    Hi Bugmenot, Why not make the latest circuit? It works very well. It is not changed much from the original, all parts operate within their ratings and the opamps are available nearly everywhere. Ivan simply reduced the positive supply voltage to the opamps then the max output voltage is low but...
  2. audioguru2

    0-30V Stabilized Power Supply

    Ivan reduced the positive supply to the TL081 opamps to only 27V so they do not have a total supply that is higher than their 36V max allowed supply. Then his project will have a max output voltage of only about 22V or less. His little 24V/3A transformer and many other parts including Q2 are...
  3. audioguru2

    0-30V Stabilized Power Supply

    Where is "the main page of the original project"? please provide a link. The original project had many overloaded parts including its little transformer. Its opamps operated at a total supply voltage that are higher than their max allowed supply voltage and even then the project did not have...
  4. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    Two 0.47 ohms resistors each will dissipate 2.9W (2.5A each) so a 5W size will be fine. The voltage across them is only 1.175V at 2.5A each so the value of R18 will need to be increased or the max current will be much higher than 5A.
  5. audioguru2

    Hyperdimensional Resonator

    I wasted over 2.5 minutes watching a video of the inventor unscrewing 4 screws to show inside the box that was almost empty. His American hill-billy accent is too stong for me to hear what some parts are called. It has something to do with time travel? But time travel is impossible. His...
  6. audioguru2

    need help in simulating the solid state power control

    You forgot to provide a link to the project so I had to look through hundreds of projects. There is no project called "solid state power control" but I found one called "Solid State Power Controller" here http://www.electronics-lab.com/projects/motor_light/041/index.html Is it the project you...
  7. audioguru2

    IC's

    I think a high value resistor uses a lot of space on an IC. A transistor constant-current-source (or sink) and a transistor current mirror work better and use a very small amount of space. A voltage regulator IC uses about 20 transistors plus some resistors and diodes. The schematic is in its...
  8. audioguru2

    opamp roll-off

    Slew Rate is the speed that the output of an opamp can change its voltage. At the frequency and amplitude where it is limited by capacitance in the circuit, changes become ramps. Sine-waves and square-waves become triangle-waves. above the slew-rate frequency limit the ramps reduce the max...
  9. audioguru2

    opamp roll-off

    The open loop gain of an opamp decreases above 10Hz. Then there is less negative feedback at high frequencies so the distortion is much higher than at lower frequencies. Opamps have internal frequency compensation capacitors for the last 40 years. The first opamps (uA709 and others) used one or...
  10. audioguru2

    opamp roll-off

    An opamp uses a single capacitor frequency compensation filter that attenuates at only 20dB/decade so that the phase shift is only 90 degrees. Since the RC reduces the open-loop gain then the negative feedback is less at high frequencies so the distortion is increased. The slew-rate limitation...
  11. audioguru2

    Portable Stereo Project: Amp Woes

    The TDA2003 is very old and it and TDA2030A ICs do not match well enough to make a bridged amplifier. A TDA7240A is a bridged amplifier made for a 14.4V supply and works well. The pcb design showed on the datasheet should be used. A supply bypass capacitor or two should be used that are also...
  12. audioguru2

    Need Help...I have (2) 25volt 3 amp Transformers and Need 1 40-50volt 3amp Trans

    I answered in the forum. Audioguru
  13. audioguru2

    120volt to +36v-0-36v transformer From (3) 12volt ct transformers?

    Hi Kyle, Once again, you do not know that a 26VAC transformer has a peak poltage of 36.8V and the rectifiers will charge the filter capacitors to about 35VDC. Your 25V transformer with two 25VAC windings will make a power supply that is about plus and minus 33VDC. The LM3886 will have an output...
  14. audioguru2

    Need Help...I have (2) 25volt 3 amp Transformers and Need 1 40-50volt 3amp Trans

    The LM3886 needs a supply of plus and minus 35VDC. The spec is written as 50W but the graphs show 60W into 8 ohms. Your transformers are (2) 25VAC. The peak voltage of 35.4V is dropped to 33.0V by the rectifiers and filter capacitors. So the output of the amplifier will be about 53W into 8 ohms...
  15. audioguru2

    LM3914 proto board

    The small pcb is single-sided. I used the vias and some edge contacts to dimmly light all LEDs then the signal caused them to get brighter.
  16. audioguru2

    0-30V Stabilized Power Supply

    The best and final circuit has been posted here many times. It uses MC34071 or TLE2141 single-supply opamps. Tesseract never said which version he used. He said he used three high dissipation output transistors for an output up to 5A.
  17. audioguru2

    0-30V Stabilized Power Supply

    The datasheet from the inventor, National Semiconductor shows the expensive LF156 with a max supply of 44V and the cheap LF356 with a max supply of only 36V.
  18. audioguru2

    LM3914 proto board

    I have some NSM3915 modules that are about 46 years old. The LEDs are dim and are red. Here are photos and the layout showing the pins:
  19. audioguru2

    0-30V Stabilized Power Supply

    Maybe Ivan did not see our modified circuit. The original project has many problems. It does not produce 30V at 3A (its max is 25V at 3A) and many of its parts get too hot so it is unreliable. Its little transformer is overloaded. Ivan's modification is not needed because the transformer...
  20. audioguru2

    0-30V Stabilized Power Supply

    The MC34071 or TLE2141 opamps are used in the latest version because their max allowed supply is 44V and their inputs work at their negative supply voltage which is 0V for U2. these opamps do not need q1 to short their output when the mains power is turned off. the TL081 opamp in the original...
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