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  1. Audioguru

    Mobile Battery Explosion

    Maybe the cell has "gassed" with hydrogen. A few of my Li-PO cells have ballooned but I didn't poke them and light them to see if it was hydrogen.
  2. Audioguru

    Solder sucker

    The internet is causing many stores to close. I like to see and hold things that I buy. If something goes wrong with them then the store replaces them. I also like chatting with the store staff.
  3. Audioguru

    Adding a light in parallel to existing loudspeaker circuit

    On the other website we told him that his 20W halogen light bulb is like a dead short circuit when cold so keep it away from the output of the amplifier. He was told that the light bulb might never receive enough signal level to produce any light and if it did light then it would flicker with...
  4. Audioguru

    How to put strong WiFi signal on 5KM Radius

    Wifi is low power two directions. Look in Google about it. If the wifi receiver cannot transmit back to the transmitter then the connection fails. A router transmits with 0.1W and wifi products transmit back with 0.1W. Yesterday I got a new cable TV/Internet provider and the low power wifi...
  5. Audioguru

    Simple SW receiver on 3V?

    The simple circuit is missing sensitivity, selectivity and automatic gain control that every simple super heterodyne AM radio circuit has.
  6. Audioguru

    Amplifier substitute PAM8403 class D amplifier

    The video shows people using a phone (no low audio frequencies and no high audio frequencies) with bone conduction but the type of transducer is unknown. Here is the horrible frequency response of a Name Brand piezo transducer:
  7. Audioguru

    Amplifier substitute PAM8403 class D amplifier

    I think those piezo transducers will sound awful.
  8. Audioguru

    Class AB Power Amplifier Design

    1) Your transistors Q3 and Q4 are tiny and will be overloaded when they drive a 4 ohms load with a 9V supply. Their current will try to be 3.5V/4.5 ohms= 778mA but their datasheet shows that they work poorly above 200mA. They will also overheat. 2) Transistor Q2 usually replaces your RB3a. Then...
  9. Audioguru

    Component values are unknown

    The Viper 06 Buck Converter shown in post #1 has its ground connected directly to one side of the electricity with no isolation.
  10. Audioguru

    Please explain this resistance reading

    A few times in my career I had a short circuit in a circuit and needed to cut pcb traces to isolate the area on the pcb the short was located. Then after replacing a shorted capacitor or semiconductor I needed to splice my cuts back to normal.
  11. Audioguru

    Please explain this resistance reading

    Your laptop motherboard might have a defective IC or capacitor. It might have a broken pcb trace. Then why measure for a short circuit when it probably does not have a short circuit? Why did you measure the resistance of a piece of wire here:
  12. Audioguru

    Please explain this resistance reading

    Simply hold the red and black meter's probes together to measure the 0.3 ohm resistance of the leads. If you squeeze the probes together very hard then you might measure 0.2 ohm.
  13. Audioguru

    Please explain this resistance reading

    Your meter is not lighted well enough to be sure but it looks like in picture #2 the meter not show 0.333 ohms. Instead it correctly shows 0.333k ohms which is 333 ohms. Pictures #1 and #3 correctly show the 0.2 ohm and 0.3 ohm resistance of your meter's leads and wires and contacts on the...
  14. Audioguru

    Component values are unknown

    The circuit posted has its ground connected directly to mains electricity so it presents a serious shock hazard and this thread should be closed with the warning.
  15. Audioguru

    Please explain this resistance reading

    Since you wrongly connected your ohm-meter to a powered circuit then you should check that it still works by measuring a resistor without any power on each range.
  16. Audioguru

    Simple SW receiver on 3V?

    Batteries have part numbers. A tiny 186 button cell is 1.5V. The 1.5V cells in a 9V battery are AAA. Then the larger 1.5V cells are AAA, AA, C and D. You select the chemistry (alkaline?) then their datasheet tells how many mAh they have for their capacity. If you want a receiver battery to last...
  17. Audioguru

    Simple SW receiver on 3V?

    Short Wave radios were used a long time ago so their circuits are old. An old audio amplifier circuit that uses a 3V supply and an 8 ohms speaker will produce only 0.05W of power. As loud as an earphone. When the battery voltage drops to 2V as it is used then there will be no sounds. If a radio...
  18. Audioguru

    DC 9v replacement

    We are guessing about the type of circuit the speaker's amplifier uses. The type of circuit plus the unknown speaker impedance determines how much current the power supply must produce. Buy then try the cheap Chinese power supply set for 9V. If it smokes and burns then buy another one that...
  19. Audioguru

    DC 9v replacement

    I figured that an amplifier powered from only 9VDC has a maximum output swing of 8V peak-to-peak if it is good, which is 2.83V RMS. Then the power in an 8 ohms speaker is exactly 1W. If the amplifier is bridged then its output is 3W to 4W into 8 ohms. A little LM386 amplifier IC produces only 6V...
  20. Audioguru

    DC 9v replacement

    I label my adapters for what they should be used with.
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