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  1. Audioguru

    What to Do With a Lot of Salvaged Speakers?

    A good speaker sounds good. Those cheap little speakers will sound awful. If they produce any bass then it will be boomy and sound like a bongo drum. They will have a shrieking peak in the upper midrange. Boom, shriek, boom, shriek. Awful sounds. In the '70ies there was a speaker project in a...
  2. Audioguru

    Reducing music in videos

    The problem of loud music in movies is caused because the movie has many "takes" and the actors and soundman learn the dialogue and think the dialogue without even hearing it. They do not realise that the loud music covers up the dialogue.
  3. Audioguru

    Low end, how to work with flicker LEDs on 1.5v

    Your YX806 IC is on my list and shows an "L" which is an inductor that looks like a resistor. The IC operates its voltage boosting at 350-420KHz. In Chinese it is called "candle flash" which might mean flickering.
  4. Audioguru

    Garden lights working on 18650 lithium single cell...

    Chinese people do not know our letter "P" then PNP is the same as NPN. A Chinese grocery store opened in my city. Their meat department had Lamp Chops because they see that our "b" looks the same as our "p". Their BBQ chickens looked like pigeons.
  5. Audioguru

    Garden lights working on 18650 lithium single cell...

    My solar garden light with the 3.3V Li-Fe-04 battery cell and a 5252F IC is marked inside to use a 1.2V AAA cell and its pcb has the voltage boosting inductor not installed. The 10440 battery cell is sold at Walmart but at the normal Li-Ion 3.7V. Hee, hee. The Chinese company who makes (or...
  6. Audioguru

    Garden lights working on 18650 lithium single cell...

    Where will you find LEDs that have matched forward voltages? From a Chinese flashlight? For the transistor to saturate its base current must be 1/10th the collector current. The 47k resistor limits the base current to only about 0.1mA so the collector current will be 1mA and each LED very dimly...
  7. Audioguru

    Garden lights working on 18650 lithium single cell...

    A solar garden light feeds about 10mA into a 3V LED for 8 hours. A 2V solar panel and 1.2V/300mAh AAA rechargeable cell is usually used with an IC that boosts the 1.2V battery voltage to 3V. An 18650 cell averages 3.7V and has a capacity of about 3000mAh so it would power the solar garden...
  8. Audioguru

    Op amp problem ua741

    The design of a 741 opamp is 50 years old! Nobody dreamed of rail-to-rail 50 years ago.
  9. Audioguru

    Low end, how to work with flicker LEDs on 1.5v

    Since the flickering LED has a circuit inside it and since it flickers when powered with enough DC battery voltage then the solar flickering light must have a boost IC, a boost inductor and it has a series Schottky diode feeding the LED with a capacitor in parallel to smooth the boost pulses...
  10. Audioguru

    Low end, how to work with flicker LEDs on 1.5v

    I have never seen a flickering solar garden light. Adding a capacitor to a solar garden light stops the voltage booster so it will not work. Instead you must add a series Schottky diode to the capacitor and LED in parallel like is used in a colors changing solar garden light. We do not know the...
  11. Audioguru

    14.4 V Lithium battery - re-purposing question

    The battery might have the charge balancing circuit inside it.
  12. Audioguru

    Low end, how to work with flicker LEDs on 1.5v

    A solar garden light has a voltage boost circuit that pulses a white or single color LED at a frequency high enough that looks steady. But when the solar garden light uses a color changing LED then the pulsing cannot be used so the circuit has a series Schottky diode feeding a filter capacitor...
  13. Audioguru

    LM358 Replacement

    I remember '1458 dual opamps from many years ago. They are completely different from LM358 because they are basically a dual 741 opamp that was released 50 years ago. The LM358 came later.
  14. Audioguru

    LM358 Replacement

    What failures are happening? The LM158 and LM358 are noisy, they have crossover distortion and operate poorly above 2kHz. All problems are caused because they use low power. Normal opamps do not have these problems but use a little more supply current.
  15. Audioguru

    LM358 Replacement

    They are completely different: 1) The inputs of an LM358 work all the way down to its negative supply that can be 0V but the TL082 inputs fail and cause the output to go high if they are within a few volts from its negative supply. 2) The minimum supply for the LM358 is 3V but is 7V for the...
  16. Audioguru

    14.4 V Lithium battery - re-purposing question

    A 14.4V lithium battery has 4 cells. It must be charged with a "balanced" charger that senses and adjusts the amount of charge for each cell. Then the battery must have 5 wires. The battery or the product it is used in (your new power supply idea) must detect "low battery voltage" of about 12V...
  17. Audioguru

    Hello, can somebody help me with an240P

    On your other thread I recommended this radio kit that comes with a 56 pages training course for high school and university about it. It comes with all parts. Look at Elenco Radio Kit in Google to see all the places that sell it including Amazon.
  18. Audioguru

    Hello, can somebody help me with an240P

    The article about making your own FM radio was printed 25 years ago when only a few people made radios themselves. Where can you buy F29 ferrite cores for radio transformers today? Maybe in a radio kit. Buy a radio, take it apart and use its parts to make your own radio.
  19. Audioguru

    Hello, can somebody help me with an240P

    An AM radio signal changes the amplitude of the carrier frequency (around 1MHz for an AM broadcast station) with the amplitude and frequency of modulation sounds. An FM signal changes the frequency of the carrier (around 100MHz for an FM broadcast station) with the amplitude and frequency of...
  20. Audioguru

    Hello, can somebody help me with an240P

    I helped you by posting a link to an AM-FM superhet radio kit that comes with a university course about how it works. Now in this thread you are asking for help with an old Japanese part of a TV sound system.
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