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  1. Audioguru

    Coronavirus transmission prevention device.

    An airplane landed in my city with two women who went to their Mecca in Iran. They were scanned OK at the airport but the next day they had the corona virus and the government asks for anybody who were on their airplane and bus. Lots of people who were crammed into cruise ships and shipping...
  2. Audioguru

    Coronavirus transmission prevention device.

    The news says that most people get the corona virus at religious gatherings like church, temple, mosque or travelling to Mecca. I will survive because I am not religious and I also stopped drinking alcohol and soda pop.
  3. Audioguru

    LM386 Alternative (Simple but slightly more power?)

    Speakers that are smaller than 3" in diameter are headphones.
  4. Audioguru

    LM386 Alternative (Simple but slightly more power?)

    I never liked the sound from expensive little Bose "one note bass" boom boxes until I saw and heard a little portable one at Cosco. It sounded fantastic but it was small and was priced $200.00. I told my son and he went to see and hear it then he searched online for a similar one and bought two...
  5. Audioguru

    LM386 Alternative (Simple but slightly more power?)

    The PAM8406 stereo amplifier IC has an absolute maximum allowed supply of 5.5V so you cannot use four AA alkaline cells producing 6V. It is rated to produce 5 Whats into 2 ohms with horrible 10% of clipping distortion. Each output will produce about 1.3 watts into 8 ohms with low distortion when...
  6. Audioguru

    LM386 Alternative (Simple but slightly more power?)

    With a 9V supply and an 8 ohm load, the LM380 and LM386 produce the same 6Vp-p at clipping which is 0.56W. They produce a maximum of only 0.45W at low distortion. Lhe LM380 has more pins for cooling so its supply can be higher then its maximum output power is higher. With a 9V supply and an 8...
  7. Audioguru

    Regulator to limit 12v DC current

    Here is the photo of a guy who ingested colloidal silver which medical experts say is not considered safe: ATTACH=full]47174[/ATTACH]
  8. Audioguru

    Regulator to limit 12v DC current

    Why would you use a rectifier to limit 12VDC current? What is the load resistance?
  9. Audioguru

    Antique "Acoustic" amp needs attention ASAP

    Instead of measuring those glass diodes, you are measuring the transformer or other circuit parts in parallel with them. I still use the HH Scott stereo receiver I bought in 1964 (it is 56 years old!) and its parts are much newer looking than in your newer amplifier. Only its selector switches...
  10. Audioguru

    Antique "Acoustic" amp needs attention ASAP

    It would be useful to have its owner's operating manual, schematic and parts list.
  11. Audioguru

    Do USB ports (for charging only) require FCC certification

    A USB port is 5V and is not a charger circuit because nobody makes a 5V battery. The Lithium battery in a phone charges to 4.2V or less, at a certain current designed for it. Instead a USB 5V is used to power the charger circuit inside the phone. Since the charger circuit does safe charging to...
  12. Audioguru

    Next Smoke Detector Millionaire or Not?

    Years ago when smoke detectors used a lot of power (vacuum tubes or TTL logic in them?) they were normally powered by the building's power but used a back-up battery of the power failed. Modern smoke detectors use very low power and modern disposable batteries power them tor 10 years (if they...
  13. Audioguru

    Next Smoke Detector Millionaire or Not?

    In Google, there is no Enegon Battery Company and there is no 9V Lithium battery with a 5V micro USB jack and charging circuit in it. The battery and charger you plug the battery into are sold only by Amazon and they probably do not know who makes them (but we know where, China). They are...
  14. Audioguru

    Common Emitter Amplifier - Class B

    Without base bias current, the transistor is turned off and does not conduct unless the input voltage is fairly high. Look at the current, it is very very close to zero. With a fairly high input voltage then a signal at the output would have severe distortion. Also, if it is biased then it would...
  15. Audioguru

    controlling amplitude of LED osc

    Of course you need to use an emitter-follower but since the output of the LM358 does not go to a high enough voltage then you need to use a PNP emitter follower like I showed. I do not think a lousy old LM358 can work with a 1M resistor.
  16. Audioguru

    controlling amplitude of LED osc

    1) Your 47uF capacitor tries to be driven with backwards polarity half the time. Connect two 100uF capacitors back-to-back. 2) The LM358 output voltage does not go high enough and the NPN emitter-follower makes it worse. Use a PNP emitter-follower instead. Mine has different battery voltage...
  17. Audioguru

    CHARGING OF EVIL FUTABA BATTERY PACK

    Energizer and Duracell also sell Japanese-made AA size Ni-MH cells that use the Eneloop chemistry that holds a charge for one year. The cells are sold pre-charged.
  18. Audioguru

    Questions lithium polymer battery

    Yes, ebay delivers fake batteries anywhere:
  19. Audioguru

    Questions lithium polymer battery

    A 18650 is a common cylinder-shaped Lithium battery cell used in laptops, vapers and power banks. It is a little larger than an AA cell. It is 18mm in diameter and is 65mm long. They are sold everywhere and some are bare and others have a protection circuit in them.
  20. Audioguru

    Questions lithium polymer battery

    A storage charge is half a charge which is far from a full charge. My RC airplanes give a warning when the lithium battery is low at 3.2V per cell then shuts off the high power motor at 3.0V per cell but allows the low power servos to work so I can steer and glide to a landing. Each airplane...
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