# Tag Info

1

Are you sure that anything is broken? This sounds like it could be normal. If you have a pair of wires that are only connected to something on one end, then that pair of wires is an antenna. An antenna will pick up whatever electromagnetic waves hit it, and the device which is connected to the antenna will see a small AC voltage as a result. In most ...

3

No, on the contrary, most if not all of them are common dynamic speakers, just small and usually employ an neodymium magnet. Many (if not most today) have a slightly different configuration from this one in the image, with a larger square coil all around the diaphragm (in order to increase power density, having the biggest possible coil for that frame). ...

2

[...]as long as the voltage supplied to the speaker measures up to ~25Vpeak from an oscilloscope, the speaker can be expected to output sound? Yes, you should expect sound out. With 25V peak sine wave applied, you could damage the speaker: from overheating its voice coil wires from distorting the voice coil form As Neil says, 40W into a voice coil MIGHT ...

1

Although it is only an educated guess, my guess would be that you are picking up interference from your power lines and/or power supply. If the hum is low, that is likely the cause. If you can verify that the hum has a frequency that is either the same as, or a multiple of the line frequency in your country, then it is almost certain that is the source. Why ...

0

The important battery voltage is not mentioned. It and the speaker impedance determine the maximum output power. With a 2.5V supply the output power is shown in a graph on the datasheet to be 0.5W into 4 ohms at low distortion or 0.8W with high distortion. With 2.5V supply, the maximum output into an 8 ohm speaker is only 0.3W with low distortion or 0.4W ...

1

You can use a 70V audio line transformers. One connected in reverse to the amp and then each speaker has its own transformer, everything will remain matched and no power lost is a resistor. You need to size the one at the amp big enough to handle the power of all of the speakers then smaller ones can be used on each speaker.

0

People are talking about a different amplifier. The datasheet for the TDA7492P rev6 IC says it is a bridged class-D type. It shows a graph of supply vs output power and it produces 15W to 18W per channel with low distortion into each 8 ohm speaker when the supply is the 20V max shown on the graph. Maybe it gets too hot with a higher supply or with 4 ohm ...

1

What you are describing is distortion. Your speaker isn't "breaking." If it broke, it wouldn't work anymore afterwards. There are a couple of possible causes for distortion in your case: The battery can't supply the needed current. Your audio signal is too high. First the battery: You are using an 18650 cell to power your amplifier. You are ...

2

I would recommend finding the schematics for this. Because it could be the speaker outputs. Attaching to the tape head circuit without modifying it might cause failure due to the line signal coming out of the phone is several times greater than the signal that is produced on a tape head. Also there are other things, like cassette present switch, actuated by ...

5

If your MCU will be analyzing AC waveforms, then you can simplify the circuit. The resistance of R1 and R3 need to be large enough so they don't affect the amp driving the speaker, 44k should be more than enough. You could also eliminate R7 if your cap voltage rating is high enough. Realize that the two stages are not independent, from an AC perspective, the ...

8

No, it is not good practice for audio, in fact it causes the circuit to not work. Imagine there are positive peaks on audio. The capacitor would always charge on the positive peak but never discharge on 0V or negative peaks. The capacitor would just slowly accumulate charge from the audio to have a voltage over it, until voltage is enough that it will never ...

0

What you're trying to do is what's been called a "Color Organ", and knowing that, you should be able to hunt down a better starting point for your schematic. You are correct (to a point) that "speaker wire would create pulses of voltage between the base and the emitter", but even once you address the issues of isolation and biasing of the ...

0

Car radios can have bridged output stages for more output power with 12VDC voltage. The speaker output signal is not at all a voltage against ground. You should use a transformer or optocoupler as isolating element. You can connect one optocoupler (=the led side) with series resistor in parallel with the speaker. The optocoupler output side feeds base ...

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