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  1. Audioguru

    LM3886 amp build

    Your circuit has no power supply voltages. Your schematic does not show the speaker connected to 0VDC. The output of the amplifier should measure 0VDC.
  2. Audioguru

    Hear like a dog - electronic ear protection modification

    No. Humans can hear from 20Hz to 20kHz. Cheap little speakers cannot produce 50Hz or less, instead they produce nothing or produce 100Hz and higher harmonics. One octave higher can produce harmonics that are also one octave higher. The relationships are not broken.
  3. Audioguru

    Hear like a dog - electronic ear protection modification

    I am old and have hearing aids because I have normal-for-my-age high frequency hearing loss. Originally the transducers were in my ear canals with soft inserts that pass sounds causing squealing feedback when the high frequencies were boosted as much as what my hearing loss needs. A feature of...
  4. Audioguru

    Building naim nap 140

    The specs for the antique Naim Nap 140 amplifier say, "45Wpc continuous into 8 ohms (bandwidth and distortion not specified)". Then maybe it produced 2nd-harmonics distortion (like an old tubes amplifier) that some people liked. Modern hifi amplifiers produce distortion so low that it cannot be...
  5. Audioguru

    There is a problem with the subwoofer amplifier circuit made by TDA2005

    You swapped the two amplifiers from the datasheet and made a few errors on their schematic.
  6. Audioguru

    Help using NPN transistors as a switch

    On the other forum, the 2N2222 transistors marked "331" are fakes.
  7. Audioguru

    Any courses or youtube where I can learn to read complex electronics schematics and drawings?

    There are many You Tube videos that are completely wrong and some show fake results. The videos are done by school kids and You Tube pays them each time somebody subscribes or watches the ad before the video plays. Many Instructables videos are the same.
  8. Audioguru

    Converting Action Figure/Toy with Leds from Button cell batteries to 5V usb wall plug help.

    Button cells cannot produce much current which limits the current since the current-limiting resistor is inside the button batteries. If an external power supply is used then it MUST use a series current-limiting resistor.
  9. Audioguru

    Regarding Battery charger IC

    Little 3V lithium coin cell batteries like CR2032 use Lithium Manganese Dioxide. They are not rechargeable.
  10. Audioguru

    Which Soldering iron should I get please?

    The tip on my Weller temperature controlled soldering iron is always at 700 degrees F. A soldering joint is finished in 1 second of time. Normal rosin-core 63/37% tin/lead solder is used.
  11. Audioguru

    Regarding Battery charger IC

    The battery shown is labelled ":LiFe" which has a lower voltage than LiIon.
  12. Audioguru

    Problem with making inverter

    Measure the output voltage with a 10.4W load (10.4W/230V= 45.2mA. 230V/45.2mA= 5.1k ohms. Then watch the transformer voltage drop as it is overloaded with 104W. 104W/230V= 452mA. 230V/452mA= 510 ohms.
  13. Audioguru

    Problem with making inverter

    The datasheet for the IRF540 Mosfet shows that its maximum allowed current is much more than 6A. Then it will get hot so a heatsink must be used and its size can be calculated. You never told us the maximum power rating of your transformer. For more power usually a larger transformer is used...
  14. Audioguru

    Problem with making inverter

    A wire gauge table shows that little 20AWG wire has a maximum allowed current of only 6A. The inverter Mosfets and transformer produce some heat so the efficiency is about 80% then the max of 6A has only about 5A of current from the 12V battery used for output power resulting in an output of...
  15. Audioguru

    Problem with making inverter

    Your 12V-0-12V transformer is fine if it and the wires can carry the needed current.,
  16. Audioguru

    Problem with making inverter

    Maybe you connected the Mosfets and transformer wires backwards. Nothing on the transformer connects to 0V except the metal frame. The drains of the Mosfets connect to the transformer outer 12V wires and the transformer center tap connects to +12V. The sources of the Mosfets connect together and...
  17. Audioguru

    Problem with making inverter

    A fake CD4047 or fake IRF540 from ebay?
  18. Audioguru

    Fisher tube amp distortion

    Antique toob amplifiers used a huge output transformer for each channel that this preamp does not have.
  19. Audioguru

    A Problem about LM2903

    Your 15V RMS input voltage has peak voltages of +21.2V and -21.2V which are destroying the comparator's input that must be within the power supply voltage which is +15V and 0V. Therefore you must attenuate the input voltages.
  20. Audioguru

    Which Soldering iron should I get please?

    Many people have trouble with a cheap soldering iron that has no temperature control. Sitting there it gets too hot which oxidizes the solder and its tip, and incinerates the important rosin in the solder. Then when used to solder a joint it quickly cools down and makes a cold joint. I have...
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