Why is there noise when I solder a circuit with speakers? 5

From the analysis of your circuit, VT3 and VT4 work in the multivibrant oscillation link, if VT2 salary cuts off. The collector potential is high, and the horn sound is normal. If the horn does not sound, VT1 must vibrate, do you use an oscilloscope to measure whether the collector of VT1 has the sine waveform shown in your figure?

If not, please exchange the two wires of L2.

When soldering the speaker strip wire, there is no requirement to set the temperature of the soldering iron, as long as the solder melts instantaneously.

The temperature is only one aspect, the important thing is that your welding time is short, and there is a process of heat transfer.

The speaker can be used as a microphone, but the impedance may not match and the sensitivity is not high.

Simple half-duplex communication is often used.

What circuits to do?

The speaker of some ** machine is a high-resistance 150, which is easy to use.

Well, yes. You can't solder the speaker directly to the motherboard, just see where it was connected before, just connect it in place.

I think the speaker would burn out if it had been used too much!

Nope....Pay more attention to the voiceover in the future.

Remove the two resistors marked in yellow, and then solder one end of the audio cable from the computer to the pad marked in red, and one soldered to the pad marked in blue (the computer is stereo, the left and right channels are two, but your sound engineer mono can only connect one channel), the audio cable is cut open, and there are three wires inside, generally red, yellow, and green, of which the red and green are the left and right channels, and the yellow line is the ground wire.

That is, the red line soldering red mark pad, the yellow line soldering, the blue mark pad, the volume needs to be adjusted from the computer.

You can use the touch test method with a screwdriver After the speaker is turned on, don't put it** Then the fingers touch the metal part of the screwdriver and touch each foot of the octagonal ic respectively Find the foot that can make the speaker make a loud clicking sound Then that foot is the audio input terminal After stringing a capacitor, the access cable can also be!

Why do you want to dismantle it? With such a thin wire, can your welder pass the test?