# How to measure capacitance without LC meter?

I would like to use capacitors salvaged from old electronics, but I currently don't have an LC meter.

What would be some really simple circuits, that would convert capacitance to something I can measure (voltage, current, frequency)?

• Not wishing to go into the fundamental ways of how capacitance is defined, to measure capacitance (or inductance for that matter) you need a reference component to compare it against. The reference component can be a resistor, an inductor or another capacitor and if you have one that can be relied upon for its value then that is a starting point – Andy aka Apr 8 '13 at 17:41
• What test equipment do you have available? – Matt Young Apr 8 '13 at 17:45
• I only have a cheap multimeter and xprotolab scope (scope, voltmeter, frequency counter) – nana Apr 8 '13 at 17:51

How it's done: you start charging the capacitor and time how long it takes to get to $\frac{1}{2}\cdot V_{in}$.
With that time (the time it takes to get to $\frac{1}{2}\cdot V_{in}$), you can calculate the RC value of the RC circuit. You know R, it's 22K in the circuit above, it's constant. So you can calculate the value of C.