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  1. audioguru2

    0-30V Stabilized Power Supply

    R1 discharges C1 when the power is turned off. If C1 is removed then the output voltage might be too high the next time it is turned on which might destroy a circuit it is powering. R2 limits the charging current for C3. If its value is too high then C3 might not be charged enough. I don't...
  2. audioguru2

    0-30V Stabilized Power Supply

    A diode bridge is frequently used in high power electronic products like this power supply. They are sold by electronic parts distributors like Digikey and Newark but maybe not by cell phone and kids toys stores like Radio Shack. They have a metal base and hole so they can be bolted to a metal...
  3. audioguru2

    Active Bass & Tremble Controller

    When the pots are centered you want no boost or cut at bass and treble so linear pots must be used. Logarithmic pots are only used for volume controls because our hearing's response to loudness is logarithmic. "TREMBLE" hee, hee.
  4. audioguru2

    0-30V Stabilized Power Supply

    Transistors are all different. There are good ones and there are poor ones. The worst (but still passing) 2N3055 transistor has a collector to emitter leakage current of 0.7mA but a good one has much less. The collector-base leakage current is much less (a maximum of only 3.5uA at 25 degrees C)...
  5. audioguru2

    0-30V Stabilized Power Supply

    The collector-base junction of a transistor has a small leakage current that increases when the temperature increases. The current gain of a transistor amplifies the resulting base current which turns on the transistor. R16 shunts the collector-base leakage current away from the base. Of course...
  6. audioguru2

    0-30V Stabilized Power Supply

    Many students use an old simulation program as part of their school work.
  7. audioguru2

    0-30V Stabilized Power Supply

    Your latest schematic should work perfectly.
  8. audioguru2

    0-30V Stabilized Power Supply

    You don't know what you are doing and I also don't know what you are doing. Your schematic shows a short-circuit and a capacitor value that is completely wrong.
  9. audioguru2

    0-30V Stabilized Power Supply

    They have the transformer short-circuited to the output 0V which is wrong.
  10. audioguru2

    0-30V Stabilized Power Supply

    Your Multisim schematic is a nightmare of crossed wires going all over the place. You changed all the parts designation numbers so it is too time-consuming to see if anything is wrong. If you SIM it in Multisim then it probably will not work. But if you build it from the corrected schematic...
  11. audioguru2

    0-30V Stabilized Power Supply

    I don't have Multisim so I can't see your schematic. Post your schematic as a screen save PNG file type.
  12. audioguru2

    0-30V Stabilized Power Supply

    You have sketched part of tthe original schematic but transistor Q3 is missing. It drives an LED that warns when the current regulator is reducing the output voltage. The current regulator does not do anything when there is no load so it is not reducing the output voltage. The original project...
  13. audioguru2

    0-30V Stabilized Power Supply

    Many things will cause the output to always be 0V. Post a PNG file of your schematic so I can see if something is wrong. Maybe your SIM software does not know the details of the special opamps that are used in the fixed version.
  14. audioguru2

    SLIGHT HELP NEEDED WITH ACTIVE ANTENNA CIRCUIT

    I think the antenna amplifier circuit is very old and might have worked fine long ago when there were not as many powerful radio, TV, taxi cab and cell phone transmitters all over cities. Now the antenna input must have a tuned circuit and AGC must be used. I use an 8 turns air-core coil for...
  15. audioguru2

    SLIGHT HELP NEEDED WITH ACTIVE ANTENNA CIRCUIT

    If you are anywhere near civilization, what will prevent the untuned circuit from being overloaded by almost every one of the thousands of powerful local signals on many frequencies? An ordinary half-decent FM tuner tunes its antenna input, then adds AGC to the Jfet to prevent overloading.
  16. audioguru2

    0-30V Stabilized Power Supply

    Set the voltage to 13.8V to 14.4V and set the current to 2.5A if you want. The current regulation will reduce the voltage to whatever the battery needs when it draws 2.5A. The voltage will slowly rise as the battery charges and the current will stay at 2.5a until the battery becomes near fully...
  17. audioguru2

    Questions about infrared cordless headphones

    Hero, please ask Mixos to remove that crappy project from this site. The guy who posted it simply copied it from a site in India without even trying it. I looked for Infrared Wireless Headphones in Google and found: http://www.scribd.com/doc/31211623/Infrared-Wireless-Headphones a final year...
  18. audioguru2

    0-30V Stabilized Power Supply

    It draws 5A at 12V when hot and it draws maybe 50A when cold. The moment that you connect it then it will try to draw 50A but the current-regulation will limit its current to only 3A by limiting or reducing the voltage. If you turn the current-setting to maximum and the voltage to zero, connect...
  19. audioguru2

    Questions about infrared cordless headphones

    Remote control is on-off. If it is used for audio then the sound will be click-click or buzz-buzz.
  20. audioguru2

    0-30V Stabilized Power Supply

    You need to turn up the current-setting pot so that the load current is less than its setting. Then the red warning light turns off and you can vary the voltage regulation voltage with the voltage-setting pot. What is the resistance of your load?
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