# Micro USB Power Supply

#### andrew74

Joined Jul 25, 2022
55
Hello everyone! I want to buy this module (https://www.amazon.it/HiLetgo®-decodifica-amplificatore-alimentazione-lossless/dp/B0797T1T87) and connect a 2W speaker to it that plays a song that I insert in the SD. I noticed from the picture that it is powered by "micro usb power supply". As this is a gift ... I want it to be portable and I want to connect the micro usb power supply to a small portable 5V battery (e.g. an alkaline battery).

(Moderator's note: Link to English version of the web page referenced above: https://www.amazon.com/KOOBOOK-Play...ule+micro+usb+5v+power+supply+,aps,389&sr=8-1)
Is this possible?

How is the connection made? I have lots of micro usb wall chargers (i.e. to plug into the wall socket), I was thinking of cutting the cable and see if I can connect wires to the + and - of the alkaline battery ... or something like this.

What type of battery do you recommend for this purpose? I've seen this classic one: https://eclats-antivols.fr/en/9v/17600-9vdc-alkaline-battery-duracell-1604-ultra-5000394005778.html ... in this link the battery is 9V but I need 5V for the module I use.

Last edited by a moderator:

#### Ya’akov

Joined Jan 27, 2019
6,856
The obvious solution to this is a one cell 18650 “power bank” that already does everything you are asking for. It produces a stable 5V, is a battery, and is rechargeable. It also probably costs less than the parts to build your own.

Since this is the obvious solution, why are you avoiding it?

#### andrew74

Joined Jul 25, 2022
55
The obvious solution to this is a one cell 18650 “power bank” that already does everything you are asking for. It produces a stable 5V, is a battery, and is rechargeable. It also probably costs less than the parts to build your own.

Since this is the obvious solution, why are you avoiding it?
You mean this one? https://www.ebay.it/itm/125386821053?hash=item1d31a30dbd:g:uk8AAOSwkUpit1gn

I had considered this solution, but I thought it was a bit "bulky", so I was opting for something smaller even though I would complicate the work a lot. I should put the amplifier module, speaker and battery attached to a small book containing photos.

#### Ya’akov

Joined Jan 27, 2019
6,856
You mean this one? https://www.ebay.it/itm/125386821053?hash=item1d31a30dbd:g:uk8AAOSwkUpit1gn

I had considered this solution, but I thought it was a bit "bulky", so I was opting for something smaller even though I would complicate the work a lot. I should put the amplifier module, speaker and battery attached to a small book containing photos.
Then I suggest a small LiPo cell with built in protection (very common and cheapish, and about any size you could want). Don’t make is so small the capacity is too low. You can buy mating JST connector cables pre-terminated if you’d like to make the battery pluggable.

Add a small charging board with boost converter, like this one, and you have your own supply. Don’t use the USB, solder directly to the +/- 5V pads on the edge of the board. You might want to add a switch that cuts off the battery.

I strongly advise against using a PP3 (9V) battery. While they have a place, most of the time they are the most expensive way to power something in terms of cost per hour of use.

#### andrew74

Joined Jul 25, 2022
55
Then I suggest a small LiPo cell with built in protection (very common and cheapish, and about any size you could want). Don’t make is so small the capacity is too low. You can buy mating JST connector cables pre-terminated if you’d like to make the battery pluggable.

Add a small charging board with boost converter, like this one, and you have your own supply. Don’t use the USB, solder directly to the +/- 5V pads on the edge of the board. You might want to add a switch that cuts off the battery.

I strongly advise against using a PP3 (9V) battery. While they have a place, most of the time they are the most expensive way to power something in terms of cost per hour of use.
The battery in the link you sent me is not available in my country so I'm asking if you think this one is OK: https://www.amazon.it/EEMB-Batteria...cphy=1008529&hvtargid=pla-1630628388154&psc=1

Adding up the price of the battery you linked with the price of the charger module, I arrive at spending about 27$. While the simple power bank you recommended at the beginning (Power Bank box 1x18650 5v 1A usb) costs only 5$.
This simple power bank does not have the two wires to be connected to a switch ... so when I want to disconnect it I simply unplug the cable.

I will try to find a trade off between price and size.

#### MisterBill2

Joined Jan 23, 2018
13,797
We do see that the pricing of different items varies a very large amount in different parts of the world. That has been a big education to me, including the aweful VAT stuck on to electronic items in the UK.

#### Audioguru again

Joined Oct 21, 2019
5,418
Amazon knows nothing about electronics so their details are only the size and the weight.
The module manufacturer erased the parts numbers of the ICs so we cannot look them up.

A PAM8403 is a similar little stereo class-D amplifier. It produces 2.3W into each 4 ohms speaker when its supply is 5V or 1.4W into each ohms speaker. With a 3.3V supply the power numbers are half.

#### andrew74

Joined Jul 25, 2022
55
Amazon non sa nulla di elettronica, quindi i loro dettagli sono solo le dimensioni e il peso.
Il produttore del modulo ha cancellato i numeri delle parti dei circuiti integrati, quindi non possiamo cercarli.

Un PAM8403 è un piccolo amplificatore stereo in classe D simile. Produce 2,3 W in ciascun altoparlante da 4 ohm quando la sua alimentazione è di 5 V o 1,4 W in ciascun altoparlante ohm. Con un'alimentazione a 3,3 V i numeri di potenza sono la metà.
[/CITAZIONE]
I can barely see this integrated here

#### Audioguru again

Joined Oct 21, 2019
5,418
Windows 10 allowed me to increase the contrast then the audio IC shows 8002A and Google lists its datasheet as MD8002A:
BL6282x (components101.com)

It operates in class-AB and it is bridged with both speaker wires driven out-of-phase.
Powered from 5V it produces 1.5W into 8 ohms with 1% distortion or 1.2W with low distortion.
it produces a lot of distortion driving a 4 ohm speaker.
The output power is less if the supply is less than 5V.

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#### andrew74

Joined Jul 25, 2022
55
Windows 10 allowed me to increase the contrast then the audio IC shows 8002A and Google lists its datasheet as MD8002A:
BL6282x (components101.com)

It operates in class-AB and it is bridged with both speaker wires driven out-of-phase.
Powered from 5V it produces 1.5W into 8 ohms with 1% distortion or 1.2W with low distortion.
it produces a lot of distortion driving a 4 ohm speaker.
The output power is less if the supply is less than 5V.
So, correct me if I'm wrong, with a 4 ohm load you get more power (2W) but more distortion (10%) ... whereas with an 8 ohm load you get less power (1.5W) but less distortion (1%).

So I would say choose an 8 ohm 2W speaker like this one: https://www.amazon.it/Altoparlante-...78742&sprefix=speaker+2w+8+ohm,aps,119&sr=8-4

#### Audioguru again

Joined Oct 21, 2019
5,418
The tiny speaker (1.5 inch diameter) has no audio specs like frequency response or sensitivity and is extremely expensive for its very poor quality. It will be a shrieker, not a speaker.

A cheap clock radio has a 3 inch speaker that is twice the size of the Amazon tiny garbage speaker.

Amazon knows nothing about electronics or audio products, instead they sell cheap clothes and shoes.
Buy from an audio equipment supplier like Parts Express.
Here is the smallest speaker (2.5 inches diameter) that sounds pretty good:

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#### MisterBill2

Joined Jan 23, 2018
13,797
Some people do not notice 20% distortion, nor a radio not tuned correctly. So for them more power at much more distortion is OK. But I would recommend the 8 ohm speakers so that the sound would be better. I do not suffer from a stone ear..

#### Audioguru again

Joined Oct 21, 2019
5,418
Some people do not hear different sound frequencies then a person singing a song sounds the same as a person reading a book.
RAP "music" is a person reading a book with a drum beating in the background.

Some people are deaf to high frequencies then they do not hear the extremely high distortion of most electric geetars that produce fuzz and overdrive. Usually those people like the screams of a cheering crowd at a ball game.

Most people with good hearing like real music reproduced with wideband frequencies and with very low distortion.

I am an old geezer (77 in two weeks). My hearing aids give me good hearing for listening to real music with wideband frequencies and low distortion. The hearing aids have selectable noise reduction that reduces continuous distortion.
It must be in my genes (jeans?) because my grandfather conducted the symphony orchestra for a large city.

#### MisterBill2

Joined Jan 23, 2018
13,797
The difference between distorted sound from a bad radio and the fuzz of an electric guitar is like the difference between a garbage truck mashing its load versus a fuel dragster coming off the line. Lots of sound, but not even close. And rap that I hear from the cars with the kilowatt sound system would be offensive if the person were reading us the phone book in that cadence and style.