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Capacitors
Capacitors store and release small amounts of electrical charge. In electronic circuits they are used to control the timing of circuits, “smooth out” electrical waveforms and to separate DC and AC components of a signal.
Capacitance is measured in Farads (F), but one Farad is much too big to be practical. Useful units are:
Micro Farads (μF or uF) = 1/1,000,000th of a Farad
Nano Farads (nF) = 1/1,000,000,000th of a Farad
Pico Farads (pF) = 1/1,000,000,000,000th of a Farad
Capacitors less than 1uF can normally go in a circuit either way round. Larger capacitors normally have a polarity (normally the negative end is marked) and have to go in a circuit the right way round.
Capacitors come in a many different types that are designed for different applications. For this circuit the type used isn't important so we've used the cheap and cheerful options. The small capacitors are “ceramic discs” and the large capacitors are “electrolytics”.
Several labelling schemes are in common use for capacitors. The ceramic discs used in these circuits are labelled with three digit codes. The first two digits are the value and the third digits is the number of zeros making up the capacitance in pF.
So:
10nF = 10,000 pF = “103”
100nF = 100,000pF = “104”
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Electrolytic polarity
Michael Faraday
(22 September 1791 – 25 August 1867)
Discovered the fundamental relationship between electricity and magnetism (amongst many things).
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