Using non-rechargeable batteries on old HP calculators

[Robert VM]

(Wonderful those time machine links to older threads)
About the size of everyday AA cells:
In a fit I filed off the button terminals from two NiMH batteries today.
Now the battery pack of an HP21 is far more easy to remove.

When I finally acquired a long admired HP67, it came without batteries or charger.
With some modifications i fitted in a Li-Ion battery (samsung galaxy s2) and used a Li-Ion charger from a camera. The modified battery looks very much like the padded AAA pack that Katie made.

I guess I should write a little text and make some photographs...

Robert