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  1. Audioguru

    What is the component

    An inductor is labeled in Henries, not it impedance at an unknown frequency. Is the impedance (reactance) of a capacitor labeled? No, its capacitance is labeled then you use math to calculate its impedance at a certain frequency.
  2. Audioguru

    What is the component

    Inductance is measured in Henries. 120 ohms is the resistance of the fine wire that has many turns. The reactance at one frequency is also measured in ohms but it is not stated.
  3. Audioguru

    Charge a 7.4 Li-ion battery through micro USB port

    Buy a "power bank" and use its USB-input charger, its single battery cell and its output voltage boost circuit.
  4. Audioguru

    Issues with kenwood KAC-511 1000w amp

    I see that he said 12 in subs which is probably 12 inch subwoofers. The amplifier specs say "continuous power into 4 ohms is 300W" but without saying how much clipping distortion. Two 8 ohm subs in parallel make a 4 ohms load on the amplifier. Then each sub gets 150W.
  5. Audioguru

    Issues with kenwood KAC-511 1000w amp

    The amplifier produces 300W into 4 ohms or 500W into 2 ohms. You are overloading it with 12 subs.
  6. Audioguru

    Wiring Tsunami Super WAV Trigger (Qwiic) to Car Amplifier/Speakers

    The low power speakers will be destroyed by the high amplifier power. The speakers are too small to produce low audio frequencies. The speakers need enclosures designed for them. The speakers are connected to the amplifier inputs instead of to their outputs. The amplifiers are rated at 14.4V...
  7. Audioguru

    LM358 Replacement

    This forum is missing a warning when entering an old thread.
  8. Audioguru

    LM358 Replacement

    An old 1458 is a dual antique 741 single opamp.
  9. Audioguru

    How do I make an opamp stereo mixer?

    The MC33172, MC34071 and MC34072 and too noisy (hisssss) to be used for audio. Use audio opamps instead.
  10. Audioguru

    How do I make an opamp stereo mixer?

    They would convert a linear level control into a logarithmic volume control.
  11. Audioguru

    battery in 0%

    A lithium battery cell is 4.2V when fully charged, 3.7V for storage or at half discharged power and is 3.2V when it should be disconnected from its load. A lithium battery cell less than 3.2V is damaged and below 2.5V it is destroyed and is dangerous to attempt charging. Many products have a...
  12. Audioguru

    Need help finding specs for old Calectro audio transformer

    A newer solid state amplifier might have used your old transformer 67 years ago:
  13. Audioguru

    Help rebuilding High School project

    Only 7 years ago he used an antique LM555 and an antique low current Cmos CD4017. At least 35 years ago I used a Cmos 555 and a high current Cmos 74HC4017.
  14. Audioguru

    Need help finding specs for old Calectro audio transformer

    What are you making that needs an old audio transformer? An antique vacuum tubes amplifier?
  15. Audioguru

    Electrets don't work

    Digikey sells only Name-Brand electronic parts. The 868 different electret mics they stock all have detailed datasheets. Amazon sells clothes, shoes and some electronic parts which are junk that they do not know who made them or if they are defective.
  16. Audioguru

    6Vdc UPS, Battery Charger for AA Batteries

    The charger is for 18650 size of Li-Ion battery cells that charge to 4.2V each and are larger than AA 1.4V rechargeable cells. It does not have a 6V output.
  17. Audioguru

    Multiple LED Driving

    AliExpress, Amazon and ebay all sell cheeep junk that have no detailed specifications. Probably manufacturer's rejects. Nane-Brand parts sold by a real electronic parts distributor are guaranteed to meet their specs.
  18. Audioguru

    Multiple LED Driving

    I doubt that LEDs from AliExpress have a manufacturers name, a part number, a detailed datasheet, a brightness level, a beam angle. The LEDs will probably not be matched. The Name-Brand LEDs I bought from a real electronic parts distributor all match the specs in their datasheet and work perfectly.
  19. Audioguru

    Coronavirus transmission prevention device.

    I normally exhale CO2, all of us do. The TV news last night said that the Covid-19 pandemic killed more than one million people in the USA. About the same number as killed in the 2nd World War. They said the Pandemic killed mostly old people and people with other medical problems. The pandemic...
  20. Audioguru

    Coronavirus transmission prevention device.

    Yes, vaccinated people can still catch the Covid-19 virus but not as much as unvaccinated people and usually with no symptoms. Unvaccinated people frequently catch the virus then need to be hospitalized with a painful ventilator and many die. Mistruths like in post #93 should not ne allowed in...
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