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  1. Audioguru

    Alternative Transistors for LM317 High Current Voltage Regulator Circuit

    Like any power supply that has current limiting or current regulation, it uses a low value resistor in series with the voltage pass transistor to sense the current then it amplifies the resulting voltage and compares it to a reference voltage. The comparator drives the ADJ pin on the LM317 so...
  2. Audioguru

    Alternative Transistors for LM317 High Current Voltage Regulator Circuit

    Yes, this simple circuit does not detect and does not control excessive current. Additional parts are needed as shown on the datasheet of the LM317.
  3. Audioguru

    My first post and help with a project

    "A" is usually a diode. A Schottky diode has less voltage drop than a silicon diode. The diode passes charging current when the solar panel is in sunshine and blocks the solar panel from discharging the battery when in darkness. "B" in most solar garden lights is part of the IC that controls...
  4. Audioguru

    Equalizier Project

    Are you making an electronic equalizer or are you making a cheap sound system that has horrible sound? An equalizer uses inexpensive electronic ICs, resistors and capacitors. It can cut or boost many frequencies that are produced by fairly high quality (fairly expensive) speakers and amplifiers...
  5. Audioguru

    Power-One power supply mod

    The new Banggood power supply has no ICs so its voltage and current regulation must be awful. There is a "doc" file about it which might have some detailed spec's but my pc no longer has Microsoft Word program to see it. Yes, I am sick of the original old power supply circuit. I have dealed...
  6. Audioguru

    Equalizier Project

    Why would anybody buy cheap Chinese speakers that have no detailed spec's? The "subwoofer" is tiny (3 inches diameter) and has no resonant frequency spec'd. They claim a response down to 90Hz (no where near subwoofer territory) but is it -3dB or is it -30dB? There is not a single word about...
  7. Audioguru

    Power-One power supply mod

    I have made many preamps but they all used a single positive supply without a negative supply. All opamps will work from a single positive supply if the input is biased at half the supply voltage and coupling capacitors are on the input, output and feedback. The preamp uses plus and minus 12V...
  8. Audioguru

    Water Proofing (light up) Fibre-Optic Vest and battery

    Why worry about waterproofing the parts? The voltage is very low so the leakage current in water will be very low. The LEDs and battery work fine when they are under water. But after many hours they might corrode.
  9. Audioguru

    Current limit for 5V @ 120mA

    For an LM317 to produce an output limited to 120mA at +5V then its input must be at least +6.75V.
  10. Audioguru

    Power-One power supply mod

    I did not look at Liquibyte's blue changes to my schematic and parts list. The transformer datasheet is confusing. It says 2 x 30V at 6A and it also says 2 x 30V at 3A. 360VA is 2 x 30V at 6A which is good because 30VAC rectified makes 42.4VDC which is 42.4V x 3A= 127.2VA and you want two...
  11. Audioguru

    Power-One power supply mod

    Yes, that is one of the latest corrections to that awful circuit. It is a shame that the Chinese company copied the original faulty circuit without seeing its faults. "Paul" in the link here (he says the Chinese kit works fine when a few parts are replaced and its maximum current is only 1.5A)...
  12. Audioguru

    Power-One power supply mod

    The schematic in your link is a copy of the old Greek kit that does not work: 1) Its output cannot produce 30VDC at 3A, it might go as high as only 25V at 2A. 2) Its 24VAC transformer will produce about 26VAC with no load then its peak voltage will be 26V x 1.414= 36.8V and the rectifier bridge...
  13. Audioguru

    Power-One power supply mod

    The ebay and Bangood power supplies DO NOT WORK (most of the parts are overloaded) and are being replaced with a kit that has a voltage and current display that is designed properly. The original Chinese kits are a copy of an old Greek kit that is/was a project at www.electronics-lab.com and...
  14. Audioguru

    Design of High Pass filter

    It is a lowpass filter that passes DC and low frequencies and cuts high frequencies. Its -3dB frequency is extremely low. A second order filter will work twice as good and a quad or more order active filter will work much better.
  15. Audioguru

    How to minimize acoustic mike<loudspeaker feedback?

    The pros use an earpiece to hear the drum beat and the pitch of the accompaniment music. But some pros do not actually sing, instead they play a recording of their singing then pretend to be singing. Some pros make many mistakes when recording so they record a song many times (takes) and pick...
  16. Audioguru

    How to minimize acoustic mike<loudspeaker feedback?

    If the frequency shift fixes a sound system that is on the edge of feedback then the shifted frequency obviously sweeps up (or down). It sounds funny. Many singers cannot sing properly when they hear an echo of their voice.
  17. Audioguru

    How to minimize acoustic mike<loudspeaker feedback?

    Frequency shifting or having a delay sounds very odd to the performer. Usually a speaker is more sensitive at its resonant frequencies, which can be equalized to not have a peak. Then there will be less feedback. Speakers are usually directional, point them away from the mic. A directional mic...
  18. Audioguru

    12v bar graph help

    A throttle position sensor should be powered from a regulated voltage. A 12V regulator would fail every time the battery is less than about 14V (idling, cranking) so maybe 5V is best. The datasheet of the LM3914 shows how a resistor from pins 6 and 7 in series with another resistor to ground...
  19. Audioguru

    555 timer

    The circuit shown is missing an important resistor in series with the base of the transistor to limit the base current. Without this resistor then the transistor and/or 555 will be destroyed.
  20. Audioguru

    Rc car: rf tx to rx

    My radio controlled transmitter and receivers use servos and a brushless ESC. I bought them already assembled from a local hobby store. I do not know which encoder and decoder they use.
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