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  1. audioguru2

    Terms for Datasheet

    Hi again, Quantum, 1) Cut-off current, Icbo, is the amount of leakage current in the C-B reverse-biased junction, with the emitter disconnected. This current is probably less at a lower voltage, and is much higher at higher temps. Note that if you connect the emitter to ground as in a normal...
  2. audioguru2

    how can i produce 15kV from 15V DC

    Hi Efra, I answered your question in your other post, except it didn't mention using a power source. Now you are even instant-messaging me. Please don't double-post. You cannot step-up a low DC voltage to a higher one using only passive devices. You must also use active devices such as an IC or...
  3. audioguru2

    Terms for Datasheet

    Hi Quantum, It is good that you are studying this datasheet and questioning its symbols. 1) The "o" in Vceo refers to its base being open, or not connected to anything (or perhaps with a resistor with a very high value connected from its base to its emitter). The transistor breaksdown (suddenly...
  4. audioguru2

    high voltages

    Hi Efra, Welcome to our forum. Of course, the laws of physics say that you can't get something for nothing. So to make a high voltage you will need a power source, from a battery of mains transformer. You can select a mains transformer to give you nearly any voltage. For stepping-up a...
  5. audioguru2

    Electronic Stethoscope 2

    Hi Doctor Emad, I can see (hear?) how reversing the terminals on the variable volume control makes the sound jumpy. I never thought of that and I am glad you discovered it. You are on the right track by reducing the gain by reducing the value of R4. But you reduced the gain too much, about 48...
  6. audioguru2

    6v drill battery

    Hi Dazza, Stuee's battery doesn't need 3A, it is rated for, "Initial current: less than 1.2A". An LM317 with this low input voltage will easily provide 1.2A (It reduces its output current with an input to output voltage more than 15V). For the circuit you posted that needs a 10V regulated...
  7. audioguru2

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

    Hi Guys, I am sorry that I made a typo error in a previous post about the zener diodes. D8 is the main voltage reference in this project and should be a BZY79C5V6, and D7 is the voltage regulator for the negative supply and can also be the same. I have edited and corrected the error.
  8. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Ngt, Welcome to our forum. 1) The guy with the 250V caps did go to sleep when he realised that they were actually 450V ones and said, "forget it". The voltage rating of a cap has nothing to do with the way it operates. Just how much voltage it can withstand without breakdown. 2) A few guys...
  9. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Zwieke, I couldn't find a datasheet for a 2N6578, but got conflicking reports about its power dissipation ability, either 87.5W or 120W on an infinite size heatsink at 25 degrees C. So it might burn. It's a darlington transistor so has an extra B-E voltage drop, which will reduce your...
  10. audioguru2

    LEDs

    Don't forget to use current-limiting resistors with LEDs! ;D ;D ;D
  11. audioguru2

    LEDs

    ;D ;D ;D I don't give up, I got it! Thanks.
  12. audioguru2

    LEDs

    Hi Cody, LEDs have a very low voltage rating. If connected across a voltage source without a current limiting resistor in series with them, they will instantly burn-out. The current-limiting resistor's value is calculated using Ohm's Law. But first you need to know the voltage rating of the LED...
  13. audioguru2

    Digital Volume Control

    Hi Giuflex, Maybe your circuit isn't this Digital Volume Control with only one IC in our projects section: http://www.electronics-lab.com/projects/audio/033/index.html Please post your circuit or a link to it.
  14. audioguru2

    Can it work?

    Hi Giuflex, That's a tricky IC that uses a supply voltage-doubler. Its channels are internally out-of-phase so that mono bass doesn't load down the voltage-doubler too much, another neat trick. Watch out about what the manufacturer says about power output. They guarantee only 45W at clipping...
  15. audioguru2

    Help needed building a room light with integrated roulette circuit

    Hi Ante, Don't you like my diodes idea? No "off" time and the driver stays cool. Your pulse-stretcher would be good for car LED turn signals. Now they switch so quickly that a quick look at the "off" time shows nothing. It would be good to have them turn-on quickly then fade slowly. A guy on the...
  16. audioguru2

    integrator help

    Hi Gauri, An RC network makes a lousy integrator. Its ramps are very curved. Your opamp integrator should be perfect. I need more information: 1) What output are you getting? Sine-wave? Square-wave? How many volts peak-to-peak? Is the entire waveform negative to ground? 2) What are the power...
  17. audioguru2

    6v drill battery

    Hi Stuee, So you're really a Brit. Have you settled into being an Aussie yet? Maybe all the blood leaked out of your head 3 years ago. ;D That's a really nice Ni-Cad fast charger that you found, but it isn't suitable for your battery's chemistry. If you simply add a resistor to its output, it...
  18. audioguru2

    6v drill battery

    Hi Dazza, Are you inviting me to visit down under? Thanks, but I can't swim that far. When I cross the time/date line, won't I have to start all over again? Sure I can help you, and Ante can too. Also invite him. He doesn't need a break yet and we'll all have a great time being upside-down...
  19. audioguru2

    integrator help

    Hi Gauri, I am sorry, but I see problems with your circuit: 1) R3 loads-down the output of U1 and is not needed. The circuit will still work with it since U1 is powerful, but it just wastes power. 2) R5 severely loads-down the output of the flip-flop and is not needed. It will make the output of...
  20. audioguru2

    Electronic Stethoscope 2

    Hi Doctor Emad, I am sorry, but it sounds like your volume control is broken or that U5 has way too much gain. The LM386 for U5 shouldn't have anything connected to its "gain" pins 1 and 8 . Then it will have a gain of 20 and very little hiss. See if pin 1 or 8 isn't accidently grounded which...
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