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  1. Audioguru

    Help to make an old analogue factory 500 amp meter become a sound meter

    The very old meter is probably too slow to show audio levels and it will probably overshoot then bounce.
  2. Audioguru

    Opamp for High Frequency Output - Need Help

    Get rid of the breadboard.
  3. Audioguru

    New (NOS) switches with contact problems -how to fix?

    I said high voltage (120VAC) and high current (1A or more) makes a spark which zaps the tarnish away. The high voltage and high current will zap the gold away if the contacts have gold plating. Low levels don't work for long with silver contacts.
  4. Audioguru

    Common emitter amplifier

    Here is the typical distortion (about 40%!) of a transistor with a high output level because it has no negative feedback, but it is not clipping:
  5. Audioguru

    Common emitter amplifier

    Clipping has nothing to do with phase or polarity. Clipping occurs when an output level is attempting to go higher than is possible. A transistor without negative feedback produces severe distortion at higher levels (but not clipping).
  6. Audioguru

    Help with diode OR gate

    Daytime running lights are supposed to be dimmed a little, unlike Chrysler and Jeep (and lately Kia and VW) who use high beams at full blast to blind oncoming drivers when it is cloudy.
  7. Audioguru

    5v from 12v is this viable?

    The text on the schematic says that "the Jfet provides a very high impedance for the pickup" and "you do not need much gain" because a guitar magnetic pickup produces a high output level. Look in Google to read about "guitar magnetic Pickup resonance" (the high frequency boost).
  8. Audioguru

    New (NOS) switches with contact problems -how to fix?

    Switches for electricity have silver plated contacts. The silver tarnishes (oxidizes and turns black) but the high voltage and current of electricity blasts the tarnish away. Low level signals use a switch with gold plated contacts that does not cost more but works "forever" with low level...
  9. Audioguru

    Common emitter amplifier

    The article talks about the phase (and very important delays) caused by speaker placement and speaker polarity. A speaker that is close to you produces sounds before another speaker that is farther away so the outputs do not cancel properly when they have a 180 degrees phase difference.
  10. Audioguru

    New Product Prototype

    It is cheap and they do not say what is the expected range. Measure the batteries voltages while it is transmitting and receiving, maybe a battery is old.
  11. Audioguru

    struggling to learn basics - 555 timer led flasher

    The datasheet for an ordinary 555 says that its minimum supply voltage is 4.5V when it barely works. The circuit does not have 22 ohms or 220 ohms resistors, they are 22k ohms and 220k ohms which are 22000 and 220000 ohms because "k" means thousands.
  12. Audioguru

    Common emitter amplifier

    Wikipedia says that an inverted signal has a 180 degrees phase shift. I agree.
  13. Audioguru

    Common emitter amplifier

    I wonder why you did not look in Google? All the articles say that a common emitter transistor inverts a signal which means its output is 180 degrees out of phase from its input.
  14. Audioguru

    New Product Prototype

    A Li-Po battery cell has an extremely low internal resistance so its maximum discharge rate is high enough to easily set it on fire. You might not find one with a rate 0f 20C anymore, 30C seems to be the minimum today. The maximum discharge rate has nothing to do with how long a charge lasts...
  15. Audioguru

    New Product Prototype

    Toy helicopter motors use a high current when started. Then the current is fairly low while they continue flying. The 20C rating is fairly low, some Li-Po batteries are rated at 70C (70 times the rated capacity current). Your existing 150mAh Li-Po cells have been over-discharged so they are...
  16. Audioguru

    New Product Prototype

    It is Chinese and is sold on ebay so it might be fake or have less than good performance (a factory reject). Its capacity is probably exaggerated. Most of the unprotected Li-Po battery cells in my drone toys have a pcb where the wires are connected with no protection circuit. If you...
  17. Audioguru

    JVC Speaker getting power but not producing sound

    You never told us that the tweeter and woofer work fine but only the mid-range speaker does not work.
  18. Audioguru

    JVC Speaker getting power but not producing sound

    The upper tweeter and middle midrange speakers are fed though capacitors that block low frequencies and block the DC from your ohm meter. Then the connector on the rear connects directly to the bottom largest woofer speaker that you are measuring 3 to 5 ohms. Then the wiring works fine and the...
  19. Audioguru

    JVC Speaker getting power but not producing sound

    Did you measure the resistance with a multimeter of the entire speaker at the connector in its rear? Is it about 7 ohms?
  20. Audioguru

    JVC Speaker getting power but not producing sound

    It is unlikely that all 3 speakers are burnt out unless it was connected to 120VAC for a fireworks show. Therefore I suspect that its main input wires are broken or quick disconnect connection has a bad crimp. Is this the connector on the rear?
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