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

[Brian Willoughby]

There is at least one company making battery boosters. These are extremely thin brackets that fit around each standard size of battery, and boost the voltage from dying batteries to normal. I'm not sure what kind of supply they use, but they work with most "dead" batteries. A serious advantage is that they work with devices (such as remote controls) where external power jacks are not available.

One possible supply uses capacitive doubling to increase the voltage (drawing more than twice as much current from the battery), but this design will still fail when the dying battery drops to half the required minimum for a given device.

Another possible supply (which might not be as compact) uses an inductor to "store" current until the induced voltage matches the regulated value. This design can guarantee the desired voltage by increasing the pulse width of the PWM controlling the switcher, but in some cases the switching frequency would have to be reduced (increasing the period) to allow for longer pulse widths.

Your approach avoids the problems with switching power supplies, but it's obviously a very manual approach. Although batteries usually have the benefit of having less noise than a switching supply, the above switchers would basically automatically adjust the voltage so you can use the powered device without constantly monitoring and replacing individual batteries.

Brian


On Dec 22, 2021, at 11:47, Jean-Pierre Desrochers <jpdesroc at oricom.ca> wrote:
> 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 !