Audio jack socket broke??

The following might answer it, you'll have to dig. I'll warn you, Quora answers are not known for being entirely accurate.

On Android phones, on iOS devices, and on HD Audio PCs, no mechanical switches in the socket are used.

Instead, the headphone socket has 4 contacts instead of 3, and accepts both 4-contact headsets and 3-contact headphones. The sleeve of the 3- contact headphone audio jack connects two of the socket contacts together.

One of the contacts is responsible for microphone and usually feeds

1.5-3.3v of voltage through a current limiting resistor (2-10 kOhm), which is necessary to bias a JFET transistor in the microphone capsule of a headset. DC resistance measurement between the microphone pin and the ground pin of the socket can be used to detect the kind of device plugged in - it will be 0 Ohm for a headphone, infinitely high for no device connected, and about 2 kOhm thereabouts for a headset with microphone.

The bias current limiting resistor forms a part of voltage divider network, with the other part being the above mentioned DC resistance. Voltage measurement on the microphone pin is taken to both determine the sound pressure on the microphone (through a 100hz high pass filter thereabouts) and the kind of jack or device inserted (through a low pass filter or noise rejection logic), allowing this design to be implemented without extra parts, if the filters are implemented digitally. Corresponding to the above DC resistances, you will measure about 0V on the microphone pin if headphone is connected, the full mic bias voltage in case nothing is connected, and something in between in case a headset is connected.

Switches in the audio jack like in the answer above were common in older electronics, but are incompatible with headsets and are just too bulky for a high-tech handset.

Quora posters steal ...

If it makes any difference, both phones are quite old, with 1 being on Android 5.0.2, and the other being on Android 5.1, and both about 7 years old now.

You could just get a Bluetooth receiver (with its own battery, e.g. Bluetooth® Audio & Hands-free Receiver AV:Link BTR1; Item ref: 100.590UK ~£10) and plug the amplifer into that. It's what I did...

Could I plug the amp into my Alexa device, as I don't want to damage that, as I may have fried the audio circuitry in both phones.

Do mean 1 like this:

I think you should first take a look at your amplifier design, and see whether it's capable of accidentally back-feeding a voltage spike into whatever you have plugged it into.

If, for example, it's a single-sided power supply design, and has a capacitor-coupled input, there's a chance that "hot-plugging" it into a device (or turning on its power when it's already plugged in) could send a pulse of current into the phone, as the DC-blocking input capacitor charges up. A device with e.g. a 12-volt power supply, which was capacitor-blocking half that much voltage, could put what amounts to a 6-volt spike into the phone output. This might have damaged the "headphone detect" circuitry in the phone.

One possibly-damaged phone could be an accident. Two, possibly-damaged with the same symptoms, leads me to suspect that the amp may indeed be at fault and could potentially damage other devices.

As I am only an amateur just doing basic circuits I watch videos on things I am interested in doing and this is the circuit I have used.

I await your verdict on it.

I don't see a problem with it, if the LM386 is working correctly and the circuit is wired up accurately. The data sheet for the LM386 has some very similar application circuits, and the data-sheet notes and schematic both show the inputs being biased down at ground voltage. No input capacitor is required, and the circuit you show doesn't have one. So, the sort of turn-on pulse I was concerned about ought not to occur.

As a check - if you have a voltmeter, try powering the amp up (when not connected to anything) and then measure the DC voltage between the two input leads (e.g. the ground shell and the tip connector on the jack). You shouldn't read more than a small fraction of 1 volt (just a few millivolts) at any time.

I put a voltmeter between the 2 input leads, GND and tip, and the reading was .002 VDC at maximum volume on the 10k pot. Nothing was connected to the amplifier circuit.

Thanks

Don't see why not. I assume the problem with my phone is just the audio socket rather than "circuitry". An "Alexa device" should have a safe input. Only you know about your amplifier input!

Exactly. Sorry the price has crept up!

Yes, no doubt it has like everything else. The price is now £11.49, oh well. Ive ordered it and await its' delivery.

thanks

If you have the same receiver I have just bought, do you get a voice message when you power it it up or down, as per the instructions. I don't and it doesn't show up in the list of devices on my phone. The blue light on the receiver is flashing, but that is all.

Thanks