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  1. Hero999

    Guitar Aplifier

    Here's the LTSpice file, plus all the required libraries. Remove the .txt extension and make sure they're all in the same directory, alternatively copy the .sub file to LTSpice's lib/sub directory and the .asy to the lib/sym/Misc directory. 10W_Guitar_Amp.asc.txt potentiometer.sub.txt...
  2. Hero999

    Power supply ignorance

    To be picky, it's not the inductance that's the problem, it's the motor's inertia causing the high current surge. An inductor would draw a small current at first which would increase linearly until it's limited by the resistance. As this particular supply can source higher currents at lower...
  3. Hero999

    resonant filtering

    Traditionally most low to medium power high frequency power supplies (<1kW) are not resonant and use PWM to adjust the amount of power i.e. regulate the output current or voltage. More modern and higher powered SMPes, typically are resonant. The employ a technique known is zero voltage...
  4. Hero999

    Guitar Aplifier

    It's oscillating. An incandescent lamp is a non-linear load, when the filament is cold, its resistance will be very low, when the filament is hot, its resistance will be much higher. The amplifier is only designed to power a 4Ω to 8Ω speaker, connecting a lower impedance load, such as an...
  5. Hero999

    Looking for a 30v varistor

    Its a bit late now but did you consider using an equivalent? Surely you could have bought a different brand of varistor with a similar breakdown voltage and energy rating.
  6. Hero999

    Guitar Aplifier

    Simulate it in LTSpice. That will give you the approximate voltages and currents you'll expect in different parts of the circuit. I'll post the files if you like.
  7. Hero999

    Guitar Aplifier

    It's pretty normal for a transformer to output a much higher voltage when lightly loaded and the mains is probably also on the high side. The circuit should be designed to account for this but this doesn't seem to be the case as the filter capacitor is specified for 35V, it should be 50V. The...
  8. Hero999

    Guitar Aplifier

    Looks good up until Q5 and Q6. That sounds right to me. Did you manage to stop it oscillating? If not then it's pointless trying to measure DC voltages because the AC could interfere with your meter causing it to generate inaccurate readings. Look at the schematic, rather than just assuming...
  9. Hero999

    Guitar Aplifier

    It's oscillating. Does it sound like a high pitched whistle or a low frequency buzz or hum? Have you turned the volume down to the minimum setting?
  10. Hero999

    How much mW is a typical IR diodes used in TV remote?

    It won't be completely invisible, some visible light will get through so you'll be able to see the filament dimly glowing red. I don't know, it depends on the type of camera, I'm no photography expert.
  11. Hero999

    How much mW is a typical IR diodes used in TV remote?

    I don't know, I would guess 800nm to 1000nm. Look at the datasheet, ask the the manufacturer. A single AA cell could be used to light an LED but you'll need a boost converter. It depends on how you design the circuit, an IR LED powered by two AA cells won't necessarily be brighter than it would...
  12. Hero999

    How much mW is a typical IR diodes used in TV remote?

    What's DSLR? IR remote control LEDs aren't that powerful, you'll need a lot of them to get 7W to 10W. 7W-10W is quite a lot of IR, certainly more than a 100W incandescent. Does it need to be continuous or is it a pulse, like a camera flash? Obviously an IR LED is much smaller than an AA cell...
  13. Hero999

    Headphone jack to antenna jack?

    An FM receiver is very sensitive and can be overloaded by high powered signals so an attenuator is required to reduce the amplitude of the signal. Use a wireless transmitter, remove the antenna and connect it to the antenna jack via an attenuator and coaxial cable. There are FM transmitter ICs...
  14. Hero999

    Guitar Aplifier

    Connecting a 470R resistor in series with the speaker makes very little difference to the the current, it increases slightly to 29.8mA. I'm beginning to question whether it's actually possible to trim the current to between 25mA to 30mA because R9 is too sensitive: with it set to 1k54 the...
  15. Hero999

    Guitar Aplifier

    R9 is 2k but 2k2 will do fine. I've simulated it in LTSpice and R9 is very sensitive, with it set to 1k5 the current is 18.9mA and when it's set to 1k6 the current is 29.6mA. I haven't tested the cross over distortion yet and I've substituted some of the transistors as I don't have the models...
  16. Hero999

    Guitar Aplifier

    Please expand further audioguru. A rheostat and variable resistor are the same thing. He appears to have connected up the resistors correctly.
  17. Hero999

    Guitar Aplifier

    You shouldn't need to vary the value of R10. Do you understand how the biasing  of Q5 and Q6 works? The voltage across Q4 needs to be equal to the VBE of Q5+Q6. The voltage across Q4 can be calculated using the following formula: VCE = VBE
  18. Hero999

    Headphone jack to antenna jack?

    It's not a case of digital or analogue, both the headphone and antenna jack are analogue. The headphone jack output is audio frequency and is a direct electrical copy of the sound wave, the antenna socket is VHF (Very High Frequency, assuming it's FM), frequency modulation. You need an FM...
  19. Hero999

    Home Page

    The site probably stores a cookie telling it not to ask you to install the language pack - try deleting the cookies for this site.
  20. Hero999

    I don't know what I"m doing wrong.......about to give up....

    Yes, you definitely need a better/hotter iron.
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