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  1. Audioguru

    Battery Drains

    Now you talk about an LED but do not say its forward voltage or its color. If it is a 3.2V blue LED then it will not light. If it is a 2V red LED then its current is (3V - 2V)/600 ohms= 1.7mA which is a very dim LED.
  2. Audioguru

    Battery Drains

    The link about the circuit says the pressure sensor has a resistance of about 2M ohms when not pressed but that the resistance varies (it could be less). It says that the slightest pressure brings the resistance down to a few k ohms. The datasheet for a CR2032 battery shows that its life (the...
  3. Audioguru

    Powering my project with a 7.4v battery

    That battery is huge. Ali is a Chinese company with horrible Engrish. In the first part of their specifications they say the wrong over discharge protect voltage and say an impossibly low temperature rating. Later in the ad they have a correct over discharge voltage but later they say that you...
  4. Audioguru

    Power-One power supply mod

    Does anybody "fix" electronics anymore? It is very reliable and if something goes wrong with it then it is simply replaced.
  5. Audioguru

    Regulator question.

    Texas Instruments' datasheet for their uA78xx and uA79xx talk about and show an input capacitor and an output capacitor on all schematics and spec's. Your tests have none then they are probably oscillating. Did you buy cheap fake parts on ebay?
  6. Audioguru

    A/C Adapter Help Please

    That kind of plug is available with a small hole diameter and a larger hole diameter. Get the correct one.
  7. Audioguru

    Power-One power supply mod

    It is much too small. Specifications are supposed to be guaranteed, but not with this piece of junk that has an ad that says the spec's might change without notice.
  8. Audioguru

    Power-One power supply mod

    Many of the parts are too small therefore will be overloaded then are not reliable.
  9. Audioguru

    Just murdered a MOSFET. What did I do wrong?

    You can buy hundreds of iRF510 Mosfets, test them all and maybe find one that turns on good enough with a gate-source voltage that is less than 10V. Maybe none are available. A 1N4003 is designed for 50Hz to 120Hz. It switches too slowly to protect the Mosfet from the very fast high voltage...
  10. Audioguru

    Power-One power supply mod

    The voltage from the 2x25V transformer is too low at 25V and it is too high at 50V. You need a transformer that produces 28V at 119VA or 30V at 127VA.Then if the circuit is modified to the latest improvements it will reliably produce 30VDC at 3A. But I do not think the larger more reliable parts...
  11. Audioguru

    Power-One power supply mod

    Banggood do not know Engrish or they do not know anything about this kit. It IS NOT the original Hyland kit, instead it is a new one with a display. I have not seen its schematic or its parts list. The photo does not show any opamps. The original Hyland kit costs almost nothing and uses the...
  12. Audioguru

    Will this LED circuit work?

    Without detailed spec's for the cheap LEDs, we do not know how much current will cause them to burn out and we do not know their actual voltage. Some red LEDs are 1.8V and are spec'd at 20mA. A 9v alkaline battery is 9.4V when new. Then Ohm's Law calculates the current to be (9.4V - 1.8V)/360...
  13. Audioguru

    Just murdered a MOSFET. What did I do wrong?

    An IRL510 is a "logic level" Mosfet and is fully turned on with its gate-source voltage at 5V (logic is usually 5V) and it does pretty well at 4V. Sorry, I do not know a power Mosfet that turns on well with only 3.3V but one might be available.
  14. Audioguru

    Just murdered a MOSFET. What did I do wrong?

    Maybe the flyback diode was connected backwards? The IRF510 Mosfet needs a gate to source voltage of 10V to fully turn on. What voltage did the "teensy" give it?
  15. Audioguru

    Will this LED circuit work?

    The cheap LEDs have no detailed spec's so they might produce a very narrow beam of light that will not be seen unless it shines directly at your eyes or they might be very dim. Blue, modern green or white LEDs will be fairly dim with the 470 ohm resistors. Use 360 ohms instead. 470 ohms will be...
  16. Audioguru

    Power-One power supply mod

    The voltage from the little transformer is too high for the opamps in the cheapo Chinese kit. but then the opamps will burn out before the overloaded little transformer burns your house down.
  17. Audioguru

    Sub Bass

    Its outputs are not sinewaves, they are sort-of squarewaves that sound like a low frequency buzzer A sinewave creates a smooth tone, a squarewave makes an irritating noise. Use a Wien Bridge oscillator with a Jfet for amplitude stability instead.
  18. Audioguru

    Sub Bass

    What is a sub bass module? Is it a low frequency signal generator that feeds an amplifier or recorder? Is it an amplifier that can feed low frequencies to a speaker? Is it a sub-woofer speaker in an enclosure? Is it a powered sub-woofer speaker that has a built-in amplifier?
  19. Audioguru

    How to minimize acoustic mike<loudspeaker feedback?

    A sound system with a half decent microphone and good speakers is usually equalized for a flat frequency response without any peaks. Then acoustical feedback can occur at any frequency if the mic can hear the speaker. The automatic notch technique will be trying to notch all sounds which sounds...
  20. Audioguru

    Newbie help - audio amplifier (BA5415A)

    Your circuit is wrong because the second amplifier has no input signal. The circuit in the datasheet applies the feedback signal of the first amplifier to the pin 9 inverting input of the second amplifier so the speaker gets a bridged output.
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