A few questions about 'gold caps'

[Rockhorst]

I bought some gold caps for a physics project (I'll share it sometime soon). These have a very small form factor, usually a disc of about 1 cm across, but a ludicrously high capacitance, like the 200 mF (0.2 F) I was looking for. They can only take up to 5.5 V though. Their main application is in motherboards and the like.

Some initial testing shows that these caps do not charge/discharge following a nice exponential. Rather, there is a fast initial step, followed by a slower exponential rise/decay. Curves match this technical guide.

I have some questions, hoping someone here is more savvy on these components than me:

- is there a way to force rise/decay to conform better with a single exponential function instead of two joined together? I kinda need that for the experiment to make sense for students.

- any other suggestions where I may find a capacitor in the range of 10 mF (0.01F) and up withouth it being quite bulky?

- these caps are quite affordable (about $1 a piece), any use for them in pedals? I'm thinking maybe capacitors for digital circuits, either high end or in the power supply of a PT2399 circuit?

[EBK]

I do wonder why you need such a high capacitance.  I will stay tuned for the details of your experiment, I guess.

I have never heard of these types of caps before.

[Rockhorst]

It's to prevent leakage over a reasonably long time and to enable kids to measure the (dis)charge curves with simple means like a stopwatch. The series resistor is only a 100 Ohms. I could bump that up to maybe a 1000 Ohms but beyond that I lose too much resolution as the series resistor doubles as a current measurements device. The point of the experiment is to determine Planck's constant by discharging a capacitor over an LED until it no longer conducts. The capacitor will remain charged at (more or less) the forward voltage of the LED. There's some caveats here, because not all electrons actually produce a photon, but I'm not going to bother the high school students too much with that.