DIY Capacitor Reference Box
This is a DIY capacitor reference box that can be used to verify and compare multimeters. It's not a metrology grade reference, but has capacitors with better tolerances than what is typically available in electronic circuits. It's still relatively cheap. For better results, a calibrated instrument should be used to check capacitor values. The reference box contains capacitors in the range from 10 pF to 10 mF. It should be said from the beginning, that capacitances below 100 pF is hard to use in a box like this, due to stray capacitances in wires, terminals and the box itself. This is discussed later below. Capacitor types There are many different types of capacitors with different dielectric and specifications. Not all of them have a stable capacitance with regards to temperature, age, voltage, DC bias voltage and other factors. The most stable ones are in general film capacitors, where polystyrene and polypropylene dielectric materials are considered best. Of smaller typ