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  1. Audioguru

    BATTERY RECHARGING DETAILS NEEDED

    Instead of guessing that 1.3V is the full voltage of a Ni-MH cell, I looked in Energizer Battery Company's website for their Ni-MH Battery Applications Manual. It shows that 1.3V is a 10% charge and discharge, it is almost dead.
  2. Audioguru

    BATTERY RECHARGING DETAILS NEEDED

    You need a battery charger circuit that will properly limit the charging current and detect a full charge (not a full voltage) then turn off. since 3 Ni-MH cells will be near 4.5V at their peak voltage then the charger needs a power supply from 6VDC to 8VDC.
  3. Audioguru

    Help with LED circuit

    Sorry, I was wrong before. Do not connect pins 6, 7, 8 and 9 of the IC to ground, instead connect them to RN1 if the linger RN1 is the same as the short RN1.
  4. Audioguru

    lipo batteries and low temperatures

    My Li-Po's and my fingers work poorly below 10 degrees C Did the Battery University say the temperature that the Li-PO gel freezes?.
  5. Audioguru

    Help with LED circuit

    You have the inputs pins 6, 7, 8, and 9 of the 74AC574 floating instead of connected to ground. Pin 3 and pin 8 of RN1 have an X instead of as shown in the schematic.
  6. Audioguru

    Help with LED circuit

    Pin 10 (0V) and pin 20 (positive supply) of the CD74AC574 are not connected to the power supply.
  7. Audioguru

    Reducing usb amps for charging small lithium batteries.

    Local hobby stores sell radio controlled drones, airplanes, cars and boats that all use 100mAh lithium batteries and sell proper chargers for them. Banggood, ebay, Ali and Amazon sell cheap Chinese copies that might not be safe to use.
  8. Audioguru

    Studio Active Monitors Speaker/Woofer Damaged buying equivalent one instead of original?

    A speaker has a long list of detailed spec's. Alexis probably do not list the speaker's spec's and the ebay speaker has absolutely no audio spec's and does not even say who made it (in their Chinese basement?). Buy a genuine speaker from the manufacturer. Whatever caused the original speaker to...
  9. Audioguru

    Solar charging 2400 mAh batteries

    I wonder how much Amazon will pay me if I give a good review of their cheap Chinese batteries that are not even made to a standard AA size?
  10. Audioguru

    Reducing usb amps for charging small lithium batteries.

    To avoid an explosion and fire, a Li-Ion battery cell must be charged from a proper charger circuit. Cell phones have a proper charger circuit inside. 5V from USB or an adapter feeds the charger circuit, not the battery cell.
  11. Audioguru

    JVC VIDEO RECORDER HR 7655 EK Loading Problem

    CDs? Oh yeah, I remember those shiny old discs. I still have a Creative portable MP3 player that has a hard drive, it is heavy and eats batteries. I used it 20 years (?) ago. I played some of my old vinyl records maybe 10 years ago. How about cassette tapes? I have a very high quality Yamaha...
  12. Audioguru

    JVC VIDEO RECORDER HR 7655 EK Loading Problem

    This is almost the year 2021. Why are you still playing with old video tapes? I use a digital PVR that records on a solid state drive. I do not know how many hundreds of hours it holds in its memory. Ultra-HD is better than old ordinary HD which was better than very old ordinary blurry and...
  13. Audioguru

    Help with LED circuit

    The transistor wired backwards might have been damaged a little since its Absolute Maximum allowed reverse-biased emitter-base is only 5V.
  14. Audioguru

    Help with LED circuit

    You are using an American 2Nxxxx transistor but you are wrongly using the European BCxxx pin locations.
  15. Audioguru

    30A LED dimmer will not work for controlling electric throw?

    My government recently gave me some LED light bulbs for free. Some of them blink off then back on a few seconds after being turned on.
  16. Audioguru

    30A LED dimmer will not work for controlling electric throw?

    Years ago my Electric Utility Company gave away compact fluorescent light bulbs for free to promote low power usage by replacing high current incandescent light bulbs. The new bulbs were No-Name-Brand Chinese and some caught on fire then dripped flaming plastic. They were all recalled and were...
  17. Audioguru

    30A LED dimmer will not work for controlling electric throw?

    We do not know if that Chinese circuit is linear then it would produce a lot of heat. A modern dimmer circuit uses Pulse Width Modulation to stay cool.
  18. Audioguru

    30A LED dimmer will not work for controlling electric throw?

    You said there is a 78L05 voltage regulator in it. The Mosfets barely turn on with a 4V gate voltage and need 10V to fully turn on.
  19. Audioguru

    30A LED dimmer will not work for controlling electric throw?

    When you buy cheap junk from over there then you get cheap junk. Maybe the rated 30A is missing a decimal point to make it 3.0A.
  20. Audioguru

    Voltage Divider Bias BJT clarifications

    In the case of DC voltage, the emitter resistor has the collector current plus the tiny base current in it. Ohm's Law says that the voltage across the emitter resistance is the emitter resistor value times the current in it. The emitter voltage will be about 0.65V lower than the base voltage...
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