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  1. Audioguru

    Alternative Transistors for LM317 High Current Voltage Regulator Circuit

    The datasheet for a 2N3055 shows that at 4A its minimum current gain is 20 and is less if its Vce is less than 4V. With a current gain of 15 then with a C to E current of 5A its base current must be at least 5A/15= 333mA. Then the voltage feeding its 470 ohm base resistor must not be less than...
  2. Audioguru

    Looking for a specific transformer

    Do you have a very high power 15V heater that uses 120A? (15V x 120A= 1800W).
  3. Audioguru

    Building an electronic foil surf board

    The internet has people converting a gas jet-ski to electric using a 30hp motor. I do not know how they avoid cavitation.
  4. Audioguru

    Equalizier Project

    The frequency response spec is meaningless since it does not say +/-3dB or +/-50dB. Since they do not say it is +/-3dB then it is probably awful at +/-50dB or worse then it produces no highs. Like most guitar speakers it probably produces a shrieking +10dB peak at about 5kHz, then almost nothing...
  5. Audioguru

    audio output transformer specs meaning?

    Speech is understood by what you are used to hearing. I find restricted high frequencies and accents cause poor understanding . Some people in Canada have a strong French accent that I have difficulty understanding. British accents are unintelligible such as them saying Wotah instead of saying...
  6. Audioguru

    audio output transformer specs meaning?

    Speech that has frequencies cutoff above 3kHz is horrible. Consonants such as with the letters s, c, t, p, sc, ch and many more are commonly spoken and reach 14kHz. You want to say the letter C, not have to say Charlie. Try to say the letter F and you need to say Foxtrot when the high...
  7. Audioguru

    Building an electronic foil surf board

    The hydrofoil lifts the board out of the water decreasing drag which increases speed. But the motor's fan must spin fast enough in the water to do it.
  8. Audioguru

    audio output transformer specs meaning?

    Voices produce frequencies from about 100Hz to about 14kHz. Much of the understanding of speech is in the high frequency consonants that are cut when a receiver has no output above 3kHz so you need to spell many words and use words for letters. The sizzle in your sidetone can be reduced with a...
  9. Audioguru

    Building an electronic foil surf board

    These little motors are designed for toy boats, not large hydrofoil surf boards.
  10. Audioguru

    Building an electronic foil surf board

    I have an RC airplane with a ducted fan brushless motor that flies very fast. I think its motor spins at 30000 RPM or more. Of course the airplane is very lightweight and does not carry a heavy passenger.
  11. Audioguru

    Powering my project with a 7.4v battery

    7.4V is the average voltage of two half-discharged lithium rechargeable battery cells in series that produce 8.4V when fully charged and the voltage drops as they discharge until they produce about 6V when they should have their load disconnected. The voltage regulator will produce an output of...
  12. Audioguru

    Equalizier Project

    You say you have tweeters and a subwoofer. The tweeters produce high frequencies and the subwoofer produces low frequencies. But you have no speakers to produce upper bass and mid frequencies. Maybe you have two ordinary mid-frequency satellite speakers and one woofer? Then very high and very...
  13. Audioguru

    Building an electronic foil surf board

    The fairly low max RPM of 3000 and graph of thrust vs speed (no Chinese translation, is 1 the speed of sound or the speed of a snail?) shows that the thruster is not made for speed. It is made for slowly pushing a submarine or slowly mooring a large boat.
  14. Audioguru

    audio output transformer specs meaning?

    An output impedance of 600 ohms is low enough for driving the capacitance of a long cable or driving the input of an amplifier. A headphones output sometimes is a high power low impedance for driving a speaker with a 220 ohm resistor in series to reduce the loudness to the headphones. An...
  15. Audioguru

    Making bad audio better

    The worst audio I have ever heard was from a speakerphone made by Goldstar of S. Korea. Goldstar was beginning to make electronic products and the soldering and circuit design were awful. The telephone system was the cheapest on the market and the company I worked for sold many of them. But the...
  16. Audioguru

    Building an electronic foil surf board

    The Chinese motor uses brushes that will soon wear out or burn out. Modern RC motors are brushless that last forever. I agree that the thrust is too low for it to carry you fast.
  17. Audioguru

    Making bad audio better

    Modern hearing aids are made for old people like me who want things to sound the same as when I was young, and they have features that normal hearing cannot do. What a huge difference it is to hear "young" again! I got a free hearing test when I was 69 and it showed that my severe high...
  18. Audioguru

    audio output transformer specs meaning?

    Have you tried it? Headphones have a common ground. If you feed the "live" wires with the signal then the earphones in series will be out-of-phase and sound weird. I think the "sizzle" of your sidetone is because it is played with high fidelity. The radio system cuts all high audio frequencies...
  19. Audioguru

    Simple LED circuit burning out

    You would also burn out if you are Chinese, you are operating at your maximum exaggerated power and are insulated by being stuck in a tight hole in wood.
  20. Audioguru

    Simple LED circuit burning out

    The product is Chinese so maybe they over-rate their stuff. Maybe the seller shipped replacements that have less power rating. Maybe your wood is blocking cooling by the "Ta=25 degrees C".
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