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  1. Audioguru

    UM66 is not giving full tone

    Since everything in India is different form here (that old Indian IC is not available in the West) then why didn't you ask about it on a forum in India? I have never asked about my Western things on a website in India.
  2. Audioguru

    UM66 is not giving full tone

    How will the doorbell pushbutton start the melody? The melody IC is designed to begin playing when the switch is turned on and stop by itself. It must be turned off by the switch so that it can start playing the next time the switch is turned on. It needs to have the switch stay turned on or a...
  3. Audioguru

    UM66 is not giving full tone

    The transformer symbol is wrong and the tone generator symbol is wrong. It should be obvious that the transformer powers this circuit so the tune plays only while the pushbutton is pressed. The datasheet of the tone generator shows how they make it work and play the entire tune. The LM386 is...
  4. Audioguru

    Simple NiMH Charging Circuit and Resistance

    My cheap solar garden lights come with a Ni-MH cell now instead of the old Ni-Cad. But the battery cell is probably 2/3rds full of rice since the AAA cells are only 300mAh compared to a 800mAh Energizer or 850mAh Duracell that are both made in Japan and might be Eneloops. The cell is cooked in...
  5. Audioguru

    Simple NiMH Charging Circuit and Resistance

    My cheap solar garden lights use a Ni-MH battery cell and it has no problem with solar charging with clouds mixed in.
  6. Audioguru

    Simple NiMH Charging Circuit and Resistance

    I trust that the manufacturer of a charger IC does everything correctly.
  7. Audioguru

    Simple NiMH Charging Circuit and Resistance

    Why don't you use a charger IC to do it properly?
  8. Audioguru

    Op amp Vcm

    You did not say that your supply is 5V, I saw the spec's for a 2.2V supply. When the input voltage is higher than the maximum Vcm then common mode rejection becomes worse and the input no longer works properly.
  9. Audioguru

    Simple NiMH Charging Circuit and Resistance

    The graphs show a "typical" battery. Some have a higher voltage and others have a lower voltage. A battery charger IC charges at 0.3C to 1C and detects the voltage drop just after a full charge.
  10. Audioguru

    Boxes. Cases. I need simple coverings for my projects! What do you use?

    I have always used Hammond plastic cases: http://www.hammondmfg.com/scpg.htm
  11. Audioguru

    Simple FM Radio receiver

    Yu are absolutely correct. Hardly anybody makes an FM receiver but many people make a simple FM transmitter without pre-emphasis. This horrible simple radio does not have the proper de-emphasis so the high noise and high distortion will be even higher than a proper FM radio circuit. The...
  12. Audioguru

    Simple FM Radio receiver

    Of course it does not have high fidelity, it is simple. It is difficult to tune and difficult to adjust the amount of regeneration, it has poor sensitivity, poor selectability, high noise and high distortion. It does not have the pre-emphasis that all FM radio stations have so it will sound...
  13. Audioguru

    Op amp Vcm

    Vcm is low on this opamp. It is from -0.3V to +1.3V for good common mode rejection. If the input is more negative than -0.3V then it gets destroyed. If an input is more positive than +1.3V then it does not work well. If you want a higher input voltage range then use an opamp with a rail-to-rail...
  14. Audioguru

    Electric ICE Exhaust Cut-out... why? and how?

    On TV in Canada there was a program about a hybrid Honda purchased because the ad from Honda said 76km range on the battery. But all winter he got only a few km and not enough power. He complained but Honda told him that is how it works when cold. He already paid $2000 for a home charging...
  15. Audioguru

    Simple NiMH Charging Circuit and Resistance

    Your voltage idea does not work because each battery cell and each manufacturer and maybe temperature changes the voltage. Didn't you learn about how a full charge on a Ni-MH is supposed to be done and how all charger ICs do it? They sense a full charge when the charging voltage drops! Here is a...
  16. Audioguru

    RCA out to 1/8" headphones on Vizio smart TV - clipping/distortion?

    The TV has a stereo output to feed the input of an amplifier, not headphones. You connected an RCA to 1/8" cord with a built-in volume control that is made to feed an amplifier, not headphones. When you connect your 1/8" connector with volume control to an amplifier designed to drive headphones...
  17. Audioguru

    Electric ICE Exhaust Cut-out... why? and how?

    Drivers at night without the lights on assume that the car turned them on because they see the dashboard display lighted and see the dim daytime running lights lighting the road ahead. I flag them down when I see them leaving a parking lot and they do not have a clue how to turn on the low beam...
  18. Audioguru

    Electric ICE Exhaust Cut-out... why? and how?

    No, only some cars do. Many people drive at night with only the dimmed daytime running lights in the front and nothing in the back.
  19. Audioguru

    Electric ICE Exhaust Cut-out... why? and how?

    Car headlights? Why aren't all cars made so that the headlights turn on when it gets dark out? Many stupid drivers drive around at night with no tail lights and dim daytime running lights. Some of the smarter drivers turn on the parking lights or the high beams when it gets dark out. The solar...
  20. Audioguru

    100K capacitor = 100pf?

    100k picofarads is 0.1uF. The datasheet for a Texas Instruments uA7815 shows a 0.1uF capacitor at the output. 100pF will not work. 10pF is stray wiring capacitance.
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