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  1. Audioguru

    Save 18650 battery

    Why do you think the chargers refused to charge the Lithium battery that has a low voltage?? Because it is dangerous! Some of the Lithium ions become metallic Lithium and cause a short circuit in the cell and explode or catch on fire if the cell is charged. Lithium is a volatile metal that burns...
  2. Audioguru

    Underdriven 12V LED chips in a 120VAC system

    There is a likely possibility of electrocution since this project has high voltage and no mains transformer then other electronics chat forums would close this thread. But I can't find the whistle for me to make an alert to the moderators. EDIT: I found and used the "report" button.
  3. Audioguru

    Underdriven 12V LED chips in a 120VAC system

    The chip producing the heat is deep inside an LED and it could be over-temperature when the outside of its case is just very warm. It takes time for the case to get hot, meanwhile the chip is cooking.
  4. Audioguru

    Underdriven 12V LED chips in a 120VAC system

    Leds are driven with current, not voltage because each LED has a different voltage and the voltage required changes with temperature changes. Cheap no-name-brand (factory rejects?) electronic items do not last long anyway.
  5. Audioguru

    How to make this circuit unity gain?

    The drive to the joining of the diodes is a way that was taught in school that I do not agree with. The opamp does not turn on each output transistor, instead the opamp turns off each output transistor. The 4.7k resistors turn on the output transistors and when they need more base current then...
  6. Audioguru

    How to make this circuit unity gain?

    First you said "NE5534" and I corrected you. Then you said the correct NE5532 IC that does not have pins for an external capacitor for each channel so it has the capacitors inside it. Your amplifier has nice low distortion.
  7. Audioguru

    How to make this circuit unity gain?

    Philips bought Signetics and took over their NExxxx ICs. The NE5532 is compensated for a gain down to 1. Philips and Texas Instruments say the NE5534 is compensated for a gain of 3 or more. They both show a 22pF external compensation capacitor for low gains. The compensation is frequency...
  8. Audioguru

    Underdriven 12V LED chips in a 120VAC system

    The internal wires and chip heat almost instantly. The frame attached to the heatsink heats up slowly then reaches its maximum temperature that is far less than the internal wires ands chip. The cheap LEDs do not have a detailed datasheet that states the thermal resistance that is stated on the...
  9. Audioguru

    Underdriven 12V LED chips in a 120VAC system

    I have never bought cheap Chinese high power LEDs so I do not know how much they lie about the power rating. Instead I buy high quality Western LEDs that meet or exceed the detailed spec's in their datasheet. I think the chip heats almost immediately then it takes time for the frame to heat up...
  10. Audioguru

    How to make this circuit unity gain?

    The datasheet from Philips shows a 22pf capacitor between pin 5 and pin 8 when the gain is 1. This class-A amplifier will have enough output power to blow up you headphones and ruin your hearing if the input level is too high.
  11. Audioguru

    Underdriven 12V LED chips in a 120VAC system

    The LEDs are very cheap. Cheap things usually have poor quality. It looks like they have 16 LEDs in series/parallel. The spec's say that some of them have a forward voltage of only 9V. If most of them are 9V then they will blow up in your circuit that has nothing to limit the current.
  12. Audioguru

    RC Parallel Circuit Measurement

    An ohmmeter uses DC, not AC so the capacitor does not affect the measurements of the resistors. A and C are the same. Then you simply have two resistors in series.
  13. Audioguru

    Need device convert hdmi to composite signal

    I haven't played my vcr for about 20 years and have not played my super 8 movies for about 35 years. Vinyl records? Compact cassette tapes? AM radio? Wired telephone? Oil fired hot water furnace? Horse and buggy?
  14. Audioguru

    Need device convert hdmi to composite signal

    A vcr was a video tape recorder and player used about 40 years ago. Do you still use one? Why? I use a modern PVR and record many shows on its hard drive.
  15. Audioguru

    Diode circuit analysis

    Its logic function is obvious: 1) When one or both inputs are low then what is the output? 2) When both inputs are high then what is the output? Its logic family was old fashioned DTL used about 54 years ago. The transistor can discharge the capacitor quickly and the resistor Rc charges it...
  16. Audioguru

    Home alarm speaker wiring

    I live in peaceful civilization so I have never seen a home alarm. What is it for? To scare away a burglar or to alert you that there is an intrusion? Smoke, CO or or fire alarm? All of the above?
  17. Audioguru

    18650 power supply

    Your quadcopter will be too heavy and not have enough power to fly. Radio controlled aircraft use lightweight Li-Po batteries designed for the high current, not heavy metal cased low current 18650 cells used in old laptop computers.
  18. Audioguru

    Impedance Matching

    His other post was closed because on another forum he is trying to make a wideband jammer.
  19. Audioguru

    My electromagnetic pulse generator

    I played the video again and used Google Translate but it didn't work. The words should be typed in the native language then Google could translate them into clear English with no echoes and no strong accent. Wye doo dey doo dat?? I doubt that people over there could understand what I say if I...
  20. Audioguru

    My electromagnetic pulse generator

    I cannot understand what is being said because there are too many echoes and the accent it very high.
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