$ 4.45 audio amplifier

Healthcare Mini Hearing Aid A sound amplifier was purchased for trial for very little money, and even that amount is not worth it.
No, I’m not so rogue that my grandmother cannot buy a normal hearing aid, she has it - a small figovina, shaped in shape under her ear, but according to the owner:
one. “The ear gets tired when I don’t take it off for a long time, itches and hurts”
2. “I save batteries that are also small and quickly drain”
Actually, for this I was looking for an alternative that would be suitable even for watching TV. Details and dismemberment under the cut.
Purchase



The choice fell on 2 devices. Surveyed and one more has not come yet, is a block on a clip with a microphone and an output 3.5 for connecting any headphones. It looks like a player, the grandmother hears music on the phone through the vacuum headphones relatively normally, so there is great hope for the last order =)
Delivered in 3 weeks. The packaging is not bad, there are 3 silicone nozzles of different sizes and a large instruction in 8 languages, including Russian.


I bought 2xLR44 "pills" for food. Well, if the batteries are inserted, you need to check. At full volume, the sound seems to be somewhere 2-3 times louder, even tapping with a finger in the microphone area does not cause much discomfort (while checking a normal hearing aid at medium volume, my father clapped his hands - I thought I was shocked). A person with a hearing impairment will not fit 100%.
But many people know about portable sound amplifiers,they are intended for healthy people, for example, for use in lectures, while watching TV at night, so as not to disturb others and not constantly listen to words, etc.
In this regard, the subject is also not suitable, because the sound is deaf, while the low frequencies are cut quite strongly. Why is this happening? Now we find out.
The whole structure is held on 3 screws. One in the battery compartment, 2 under the rear flap, which does not look like a flap and was torn off by accident.

That's actually the whole filling, the role of the amplifier plays MC31119, which works in a wide voltage range and can deliver 250mW at 32?, amplifying sound up to 46dB. There is potential (as I understand it, there is a function for dynamically adjusting the volume).

I can’t say anything on the microphone - I didn’t unsolder, there is no marking on the case. You can also see the compound, which was used to cover the speaker plug.

The speaker is film (not strong in varieties), as it used to be in the Tetris toy, only less.

I thought the resistance would be standard for similar ones - 8 ?, but no, measuring 31.8 ?.

The speaker plug is round, plastic, closes the landing hole tightly, for some reason, protective films are glued on both sides.

Is the speaker resistance close to the resistance of the headphones that were lying in the box without a socket, 31.8? against 34.5? earphone.

I thought the sound would get better, soldered, but duringamplification, extraneous squeaking noise appears (the cord is long, the earphone is vacuum), in complete silence it does not squeak. Most likely the circuit was tuned to the resistance of the installed speaker, 2.7 resistor? I did not find, so I can’t check. The only thing I tried was to connect the two headphones in series / in parallel, getting ~ 17/70? accordingly, only the tonality of the noise changed.
To summarize:
Pros:
The device works and does not look miserable, on40mAh consumes maximum volume (it is not convenient to hold both probes and take pictures, so just believe). Soft softtouch “stick” for fastening behind the ear - you can reel on any, auto-adjust the volume (easy noise reduction).


Minuses:
The device is shitty, sound ... ifturn up the volume in the player, cover the headphones with a plastic cup and press your ear against it, that's about the sound the device gives out. Also, the leg on which the mount on the ear rotates is not a part of the body, but a separate stray screwed by a self-tapping screw, and it, in turn, is unscrewed during rotation (glued it with superglue to the body)

Not happy with the purchase, and not just me.

Those who have suggestions for revision - I will listen with pleasure. I know how to hold a soldering iron in my hands, in the evening after work I can pick out something.