[sdiy] Outside Synth DIY topics but could be of some interest..

[Roman Sowa]

When one of the batteries is more dead than others, at certain current 
(it may be as low as few mA) it will be too weak to hold and becomes a 
resistor. It will actually reverse polarity and take most of stack 
voltage on itself, so entire stack will drop from say 20V to 1V.
To prevent that you might add ideal diodes over the cells. Those are 
widely used in solar panels.

And what a coincidence, few emails later I have found a spam about 
MAX17220 DC booster, it ideally matches the topic of wringing nearly 
dead batteries. It starts from 0.88V input and then works until battery 
is 0.4V dead. Only 4 external components and output adjustable from 1.8 
to 5V.

Once I got a thing from Aliexpress, basicaly a PCB with booster on it 
and battery clips. So you put a dead AAA battery in and hapily enjoy 5V 
at its output until poor battery wheeps "please let me go now...".
It was about $1 IIRC

Roman


W dniu 2021-12-22 o 20:47, Jean-Pierre Desrochers pisze:
> Hi all,
> 
> Here is an idea (outside DIY synth) I had sometime ago..
> I hope this could be of some interest for you  guys..
> 
> Tired of throwing away lots of 'end of their life' batteries
> when they reached 70% or less of their original values
> and you could not use them for other stuff ?
> Well I accumulated a lot of AA type batteries over the years
> and kept them in case of.. Happy I did so..
> Here is a small project I made to re-use them and even more,
> use them as a variable voltage supply..
>   
> http://www.arcenson.com/projects/Battery_Pack/
> 
> In this project, over time, I can spot the 'going almost dead' batteries
> using the small voltmeter and comparing successive rotary switch voltages
> then following the battery's chain number and remove/replace it
> with another 'used' battery.
> 
> In my case this small box will be used to supply small battery operated
> devices
> while repairing or testing them.
> This thing can supply up to 24 x 1.5vdc = 36vdc (with brand new batteries)
> but this is not the primary goal of it.
> Here, with used batteries installed I could reach up to 29vdc
> which is not bad with 'about to be thrown away' batteries !
> 
> Merry Christmas to you all !
> 
> Jean-Pierre Desrochers
> 
> *********************************************************************
> 
>> -----Message d'origine-----
>> De : rburnett at richieburnett.co.uk <rburnett at richieburnett.co.uk>
>> Envoyé : 13 décembre 2021 08:02
>> À : Jean-Pierre Desrochers <jpdesroc at oricom.ca>
>> Cc : Synth-diy at synth-diy.org
>> Objet : [Polluriel détecté] Re: [sdiy] My good old VGA oscilloscope
> plugged to
>> my modular..
>> Importance : Faible
>>
>> Very pretty!  The perfect use for that old 4:3 analogue VGA monitor that
>> everyone still has in the cupboard gathering dust.
>>
>> -Richie,
>>
>>
>>
>> On 2021-12-12 21:35, Jean-Pierre Desrochers wrote:
>>> Here is a short video of my 2015 open source VGA Oscilloscope project.
>>> It's made out of a small Microchip PIC micro with the help of some
>>> analog comparators circuitry.
>>> This box produces a vertical line that follows the incoming stereo
>>> audio signal connected to it.
>>> It then drives an external VGA display.
>>> A choice of 7 different colors can be applied to the vertical line.
>>> It just needs an old 4:3 VGA screen with a 800x600 resolution.
>>>
>>> https://www.youtube.com/watch?v=VKMjb3CpOCE&t=135s
>>>
>>> Enjoy !
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> 
> 
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