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  1. Audioguru

    TS to TRS microphone

    Is your microphone a dynamic type (coil and magnet) or is it an electret type (condenser mic with an electret voltage source to bias it and a Jfet that must use external power)? I assume that the Ring terminal is what applies power to an electret mic and is not used with a dynamic mic. The TS...
  2. Audioguru

    Voltage Divider Bias BJT clarifications

    A transistor has a base to emitter impedance as shown on the datasheet of a 2N3904 transistor. When an emitter resistor is added then the hfe gain of the transistor increases the effective value of the emitter resistance which increases the transistor input impedance since it is in series with...
  3. Audioguru

    Solar charging 2400 mAh batteries - Part 2

    Old cheap solar garden and post lights used a solar panel and LDR with plastic covers that got sunburned and cloudy so they soon became useless. They also used a very cheap low capacity Ni-Cad battery that rusted and failed soon. Modern ones use a solar panel with a glass cover and a higher...
  4. Audioguru

    3.5mm stereo audio jack

    Your cable does not look like a stereo audio cable because the signal wires do not have a shield. Your cable simply has 3 unshielded wires in it. It will pickup hum and all kinds of other interference unless it is used to feed low impedance speakers or headphones.
  5. Audioguru

    Signal lenght detection

    The LM3914 LED driver used amplifies and rectifies the signal so that its outputs produce regulated current-to-ground to turn on an LED that has its anode connected to a positive voltage. But the Pulse Width Detector circuit shown in post #3 needs a positive pulse as its input.
  6. Audioguru

    Large Currents vs Small Currents

    I do not know anybody who uses a powerful alternator so that they live all the time in their car. I guess it is connected directly to the battery and does not cause the cigar-lighter fuse to blow.
  7. Audioguru

    Large Currents vs Small Currents

    I have never tried to do welding so I cannot think of anything else that I would make that uses the extremely high DC current of 100A.
  8. Audioguru

    Large Currents vs Small Currents

    Note #5 in the datasheet says its case has a max drain current rating of 75A. I doubt the little pins will survive 75A.
  9. Audioguru

    Step down transformer

    The solar panel on a cheap solar garden light is a weak little thing. A dead battery (after a week of clouds) shorts it for a while as it slowly charges the battery.
  10. Audioguru

    Step down transformer

    The solar garden lights are designed to be charged from a low current solar panel. Remove the batteries to avoid the external unlimited current from exploding them then connect the voltage converter set to 1.25V directly to the battery contacts on the circuit with the correct polarity. The...
  11. Audioguru

    Large Currents vs Small Currents

    The datasheet for the LM555 and uA555 show spec's stopping at 200mA where the maximum voltage drop is very high at 2.5V and the graphs showing typical ones stop at 100mA. I believe that Mosfets have a high gate to source capacitance and very low on-resistance because they are made with...
  12. Audioguru

    Large Currents vs Small Currents

    No. The datasheet says 200mA. [fixed quote error :) ]
  13. Audioguru

    BJT vs MOSFET for logic gates help

    A symbol should not need a label on it to what is what.
  14. Audioguru

    BJT vs MOSFET for logic gates help

    The symbol for a Mosfet should be standardized. I have never seen a datasheet of a Mosfet that has a circle on the gate like an inverter and that is drawn completely symmetrical so you cannot easily see the Source pin. I have also never seen the arrows backwards. Hee, hee. Just now I looked at...
  15. Audioguru

    BJT vs MOSFET for logic gates help

    I listed 4 types of logic circuits that worked perfectly and have been used in many circuits over the years. But you are listing impossible logic that will not work. The circuit types I listed were made into ICs and computer processor chips. You are not even using any ICs that are readily...
  16. Audioguru

    BJT vs MOSFET for logic gates help

    Why are you guys trying to re-invent digital logic when there is already a history of logic types: 1) RTL resistor-transistor logic. 2) DTL: Diode-transistor logic. 3) TTL: Transistor-transistor logic. 4) CMOS: Complementary MOSfets logic. Here is a very odd Cmos circuit posted by Tristan in...
  17. Audioguru

    Solar charging 2400 mAh batteries

    Look what I found on my desk! It is a very lightweight AA Ni-Cad cell Made in China with a 250mAh rating. It is dated 2018. I betcha it is mostly filled with rice instead of with battery chemicals. I have never used it but it still holds a charge from the factory. I found another Ni-Cad AA cell...
  18. Audioguru

    Solar charging 2400 mAh batteries

    Punish the poor but not the rich? My local university has MANY students from (name of foreign country) who drive very expensive new sport cars that have had their mufflers and pollution controls removed. Some of them are fined but the thousands of dollars is nothing to them. The poor kids also...
  19. Audioguru

    Speakers in series - capacitor

    You have a subwoofer with a crossover at 150Hz and you have tiny tweeters but you do not have a woofer/midrange speaker for frequencies in between. So maybe the 8" speaker is a single-channel woofer and has a crossover at 2kHz and the tweeters are ordinary little 2.5" speakers, not tweeters and...
  20. Audioguru

    Solar charging 2400 mAh batteries

    Many people (animals?) deposit beer cans on the street. Some people (animals?) have the muffler and pollution controls removed from their cars. Some people (animals?) do not pickup their dog's droppings.
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