EEVblog #1094 - Casio FX260 Solar II Calculator Experiments

[EEVblog]

Some experiments on the Casio FX260 Solar II scientific calculator.
Improving the solar capacity, trying out a Tritium nuclear battery!, current measurement, and probing of the PCB and LCD signals.
BONUS FX991EX Teardown and soldering iron burn!

[max666]

If we're talking tantalum and super cap, isn't going overboard on capacitance detrimental to low light performance, due to higher leakage current of the cap?

[EEVblog]

If we're talking tantalum and super cap, isn't going overboard on capacitance detrimental to low light performance, due to higher leakage current of the cap?

Could be in theory, but tantalum leakage is in the order of a uA or less. Niobium oxide is usually slightly higher.
Operational current was measured at 30 times that, so should be fairly negligible. Closer margin in lower light, but I don't think it'd be a problem. Worth checking though.

[Fungus]

Does it still charge the cap when it's switched off?

Turn-on delay will be zero if so.