small variable capacitors (measured in uF)? measuring capacitance?

Mad Scientist Jr wrote in news: snipped-for-privacy@w5g2000hsg.googlegroups.com:

They'd be HUGE. Easily as big as a fridge or a car, even a truck in the case of 220 µF.

What matters is the timing, as it's timing that matters in amps and synthesizers, except for power supplies or sample and hold circuits where capacity is more important.

To get long timing with small capacitors, use large value resistors, and make sure you have low leakage capacitors.

Also, use a fixed capacitance and vary the resistance. That's what is usually done, and is why variable capacitors are rare.