Power Supply Advice Please

[Deltatango]

I have made a newer version of my battery powered power supply, my old one was a LM317 with 10x AA batteries with variable output worked well but needed a bit more voltage.

Building around a China made kit on sale with 2A output and 24v AC input, while I would not always need that power for my service work on small items, I will power it also with AA's as they are cheap using mid range brands. My question is :-

1) 24v battery pack direct.
2) 24v battery pack feeding a DC-DC step up covering input voltage drop off as they tire.
3) 12v battery pack (x2) feeding a DC-DC step up which also covers battery fade but has more current for the converter.

Thanks for any insights and thoughts

David

 

[BradtheRad]

In my mind I've dreamed of building step-up converters that let me put one battery in devices that run on 3 or 4 cells. Incandescent flashlights, LED flashlights, a clock, a thermometer... I could deliver the full voltage the device needs, with only the one cell to test and/or replace. However there's the headache of fabricating an enclosure for such circuits. It ought to be a small battery-shaped shell whose electrical contacts match a battery and also the ends of the compartment.

You might manage okay with a few cells and a buck-boost converter. And with less wasted power. As you know the 317 regulator is resistive drop. And doesn't the 317 subtract a volt or two?