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  1. Audioguru

    Replace IC 4049

    The transistors are ordinary complimentary emitter-followers. Emitter-followers do not need a series base resistor. The NPN pushes the gate high and the PNP pulls the gate low (push-pull). They have low input current but enough output current to quickly drive the high capacitance of the gates of...
  2. Audioguru

    Diy generator

    Windmills need something to prevent them from spinning too fast in a strong wind and hardly any load. To prevent the "shovel blades" from flying apart and injuring nearby people.
  3. Audioguru

    Diy generator

    Usually electricity is produced by windmills and waterwheels driving the generator. Can you use Nuclear in school? Many homes today have solarpanels on the roof making electricity.
  4. Audioguru

    Need help with LDR circuit

    Both if your circuits do the same thing. When the LDR has light on it then the transistor and LED strip turn off. When you cover the LDR then the transistor and LED stop turn on. Your circuit is wired wrong tor it to operate backwards.
  5. Audioguru

    Need help with LDR circuit

    Your schematic shows an LDR (not an LED) that turns off the NPN transistor and LED strip when the LDR has light on it. Then the LED strip turns on in darkness which is what you want.
  6. Audioguru

    vcr head diag

    This is 2021, not 1981. A VCR is an antique, A PVR with a solid state memory is used now.
  7. Audioguru

    Converting Bluetooth headphone to hearing aid.

    Most old people like me have high frequency hearing loss but low frequency hearing is normal. At 75 years old my hearing needs a lot of programmed high frequency boost so the electronics of my hearing aids with the microphones are on top of my ears and the tiny speakers are inside my vented...
  8. Audioguru

    Stage0 - a $20 wind turbine charging AA/AAA rechargeable batteries.

    You said that your AA size Ni-MH batteries are only 1400mAh which is almost half as much as Energizer or other Name-Brand batteries. If you bought them from ebay then look online for battery tests that show some batteries from there are useless. Here is a You Tube test of some "crappy" Ni-MH...
  9. Audioguru

    Audio - TV Extension Speakers

    David the thread starter says he is old and "I hear too much bass (senior thing) and turning up the volume just seems to drown out the treble and speech becomes muffled." I am 75 years old and my hearing was like that until I got hearing aids with the extreme amount of high frequency boost...
  10. Audioguru

    Stage0 - a $20 wind turbine charging AA/AAA rechargeable batteries.

    Here is one of many videos about ebay fake batteries:
  11. Audioguru

    Stage0 - a $20 wind turbine charging AA/AAA rechargeable batteries.

    ebay and others sell "Super-Heavy-Duty" batteries cheaply that are old carbon-zinc garbage. Recently I bought Duracell Ni-MH batteries and a fast charger at a very low price at Costco. 8 Batteries for the cost of 4 anywhere else plus a free charger. BUT the fine print says, "Made in China" and...
  12. Audioguru

    Audio - TV Extension Speakers

    Like I said, you and I have high frequency hearing loss that is normal for seniors. A treble tone control turned up to maximum is not enough and it would drive away anybody who has normal hearing. You need a free hearing test and hearing aids programmed for your hearing loss.
  13. Audioguru

    Audio - TV Extension Speakers

    My hearing got worse as I got older so I went for a free hearing test when I was 69 years old. The results were normal for my age and needed double the amount of treble boost that my stereo could produce. They programmed and loaned me modern hearing aids that worked perfectly so I bought them...
  14. Audioguru

    Trying to use existing 18v li-ion charging cradle

    I get to Farnell flags by keying farnell.com into Google. The places ln the world are called Element14.
  15. Audioguru

    Trying to use existing 18v li-ion charging cradle

    For Chester hill Australia go to www.farnell.com and click on the Australian flag. It is one of the many Farnell (based in the UK) electronic parts distributors all over the world.
  16. Audioguru

    Trying to use existing 18v li-ion charging cradle

    When a Li-Ion cell reaches its max allowed voltage of 4.2V it is far from a full charge. The charging circuit keeps charging it until its charging current drops to 1/10th or less of its mAh rating, then the charger shits off. EDIT: Maybe your charger shits off at 21V. Nobody makes an accurate...
  17. Audioguru

    Stage0 - a $20 wind turbine charging AA/AAA rechargeable batteries.

    Panasonic now owns Sanyo and their Japanese Eneloop batteries have new chemistry that holds a charge for one year. Energizer Ni-MH batteries are also made in Japan with new chemistry that holds a charge for one year. Batteries from ebay leak and hold a charge for only a few minutes.
  18. Audioguru

    Trying to use existing 18v li-ion charging cradle

    You forgot to tell us the chemistry of the battery. If it is 5 Li-Ion cells then it needs 21.0V and a proper lithium-ion charging circuit which might be in the original power supply or in the cradle. A hobby store will have a charger for 5 Li-Ion cells.
  19. Audioguru

    Stage0 - a $20 wind turbine charging AA/AAA rechargeable batteries.

    The very cheap motors used as generators have simple brushes and simple bearings that will soon wear out. What circuit (a diode?) will you use to prevent the batteries from wastefully powering the motors and spinning the windmills when there is no wind? A simple electronic circuit like used in a...
  20. Audioguru

    BATTERY RECHARGING DETAILS NEEDED

    The charging voltage is higher than the discharging voltage which is why charging to only 1.3V is an almost dead battery.
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