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  1. audioguru2

    n-chanel enhancement mode power mosfet

    Hi Alun, You circuit has lotsa gain! You could mount a propeller above the hot 47 ohm resistor and use it to propel the car. ;D
  2. audioguru2

    Soldering Station Confusion

    The guy was soldering LI-Po cells together. They have polyester inside and all around them. Even their heat-shrink plastic case didn't melt. I soldered button cells when I was young and didn't know anything about danger. About as crazy as soldering a car battery. Did you use a blow-torch? ;D
  3. audioguru2

    Soldering Station Confusion

    My Weller WCTP's have never caused thermal damage to anything with their tips that keep their temp at 700 degrees F. Most of the time I don't even bother using pliers as a heat shield. Many thermally-sensitive components have a duration limit for their exposure to a high temp. A lower temp of a...
  4. audioguru2

    Basic Car Audio Electronics

    Thanks Tekker, That great site even talks about the IDIOTS who are beyond idiot status that go around with their car stereos blasting Boom-Boom and foul language. ;D
  5. audioguru2

    n-chanel enhancement mode power mosfet

    A modern Mosfet works the same or better than a relay. It conducts better than the connection wires and battery's internal resistance. Make sure you connect a reverse-bias diode across the relay's coil to arrest flyback voltage spikes. Relays are guaranteed to activate at 0.75 of their coil's...
  6. audioguru2

    Increasing the range of Transmitter

    In some countries all unlicenced transmissions are illegal. Here in Canada, the allowed power is very low. Someone built and tested my 1/4W FM transmitter and saw the RF cops go by later with their truck with the antennas on top scanning for him. I got busted for my sparking fan. You might get...
  7. audioguru2

    class of amplifier

    Hi Alun, The complimentary emitter-followers won't oscillate due to positive feedback into them through the 68 ohm resistor: 1) An emitter-follower isn't perfect so will have a max voltage gain of maybe 0.95 with a low resistance load. It is less than 1.0 so it can't oscillate. 2) The open-loop...
  8. audioguru2

    n-chanel enhancement mode power mosfet

    Hi Goatman, If the voltage went to half the supply when the transistor was powering the motor then it might be getting very hot. Just look at the datasheet for the 2N3055 and use arithmatic to see if it will blow up: 1) You don't say how much max current the motor uses, but assume it is 10A...
  9. audioguru2

    Micro battery charger

    Hi Prateek, The choice of using a rechargable battery or super-capacitor (many Farads) depends on their strengths and weaknesses: 1) I have some 1W walkie-talkies that use three rechargable AAA Ni-Cads. Each charge powers them for about 6 hours if I don't transmit much. For the small size and...
  10. audioguru2

    n-chanel enhancement mode power mosfet

    44% more than its power rating doesn't sound like it is good for the motor. Doesn't it have a variable speed control? Impossible. Most Mosfets are spec'd with a 10V input. I think that the transistor connected to your blown Mosfet is another blown Mosfet that was in parallel with it. I have seen...
  11. audioguru2

    n-chanel enhancement mode power mosfet

    Hi Alun, You're relying on typical values for design spec's. Ron Mancini, a scientist at Texas Instruments agrees with me in his recent article titled, "How to read a semiconductor data sheet" in EDN here: http://www.edn.com/article/CA514964.html?industryid=2281&nid=2433 He says, "Typical...
  12. audioguru2

    class of amplifier

    Hi Alun, My circuit has proper negative feedback, the transistors don't invert, they are just followers. I very carefully matched the 39k feedback resistor to the 33k in series with the two paralleled 10k resistors so any high input current opamp can be used without offset voltage. I also...
  13. audioguru2

    TRANSISTOR ATTENUATOR?

    Feeding a signal to the collector varies the collector and emitter current. Therefore the emitter's resistance, Re, has a varying voltage across it. Since it is also in series with the base-emitter junction, the base voltage varies a little amount. The signal at the base is not the same...
  14. audioguru2

    Micro battery charger

    Hi Prateek, You spell spacific like a blue-blooded Frenchman! Check-out www.energizer.com and click on Technical Info. They have tiny button and coin shaped battery cells, some that use lithium. They have a shelf life of at least 10 years and pack a lot of lightweight endurance. They also have...
  15. audioguru2

    Soldering Station Confusion

    The heat setting on my simple, long lasting temperature controlled soldering iron is automatic. For a mass of metal and rework, it automatically goes to full power until the desired temperature is reached very quickly. For fragile items or at idle, it uses very little power but is ready to...
  16. audioguru2

    New member says hi!

    I taught my teachers and professors lotsa things that I learned from magazines and IEEE documents at the library. I made every assignment years before they were due. When the class was learning about resistors and capacitors, I was making transistor and logic circuits.     Yeah: the joys of...
  17. audioguru2

    n-chanel enhancement mode power mosfet

    Hi Goatman, Welcome to our forum. ;D All Mosfets have an extremely high input resistance but a fairly high capacitance. If the input must switch at a high frequency for pulse-width-modulation control of the motor's speed then adequate current must be provided to charge and discharge it. Most...
  18. audioguru2

    class of amplifier

    Hi Alun, In 1980, telephone interconnect came to Canada and the sound systems company I worked for decided to sell and install phone systems. Instead of selling the same ones as other companies they decided on a phone system from a little-known Korean company called Goldstar (now called LG...
  19. audioguru2

    Soldering Station Confusion

    Hi TekNoir, Welcome to our forum. ;D I have used Weller WTCP irons at home and at work for about 40 years. They don't have instant temperature adjustment nor a fancy display that I have seen on much more expensive ones fail during a lightning storm like my cheap clock radios. At first I tried...
  20. audioguru2

    class of amplifier

    Hi Alun, An Englishman named John Linsey Hood developed a "Liniac" small amp in the 70's. It used a darlington and current source for extremely high gain and very low distortion with negative feedback. He reported that the darlington multiplied its own small capacitance and it created a low...
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