Capacitors

This page is not complete and still under construction beware of errors and omissions

Last updated 18/03/99

We keep a range of Capacitor values and types in stock. As a quick guide we keep decade values of 1, 1.5, 2.2, 3.3, 4.7, 6.8. In the values 10pF to 470uF. As a general rule capacitors have a poor tolerance rating in the region of 15-25% sometimes as low as 50%. It is for this reason that there is a limited value range. High precision capacitors are available but at a much higher price. Below is a brief guide to the value and type of capacitors we keep in stock.

Capacitance is measured in FARADS. Generally capacitors are measured in uF (Micro Farads), nF (Nano Farads) or pF (Pico Farads).

  • 1uF is 0.000001 Farads or 1X10-6 Farads (or : 1000 nF : 1,000,000 pF : 1 uF)
  • 1nF is 0.000000001 Farads or 1X10-9 Farads ( or : 0.001 uF : 1000 pF : 1 nF)
  • 1pF is 0.000000000001 Farads or 1X10-12 Farads ( or : 0.000001 uF : 0.001 nF : 1 pF )

    •  Value range Material

    Approximate Tolerance
     10pF to 100nF Ceramic 15% to 70%
     10nF to 4.7uF Polyester 10% to 20%
     10pF to 10nF Polystyrene 2% to 5%
     1uF to 1000+uF Electrolytic  +/- 20%

    The capacitance of a capacitor is usually indicated on the body of the capacitor by a code such as :-

    If you see a code such as 102 (a letter may follow this figure) this equates to 1 : 0 : 00 and the capacitance in pF, 1,000pF or 1nF or 0.001uF another example e.g. 471 is 470pF.


     

     

    The Alphanumeric code is usually the easiest to identify and will be written as 1uF, 1nF and 1pF, a Maxium working voltage rating and even a working temperature range maybe included. On electrolytic polarity lead identification is also included, on the 22uF capacitor shown the -ve lead is shown (left lead), the titanium capacitor on the right (2.2uf 35V) has it's +ve lead identified i.e the right hand 'leg'.Electrolytic capacitors are polarised that is they have a Positive terminal and a negative terminal, these capacitors must be used the correct way round and will be severely damaged if used the wrong way round.

     

    The Colour-coded capacitor is read in a similar way to the resistor colour code no tolerance is indicated and the capacitance is in pF. The other bands are for voltage rating. This form of marking capacitor values is not used much nowadays.

    Capacitors come in differing package styles, physical size, voltage ratings and dielectric materials. Each has particular properties and specific usage's. For a more detail insight in to capacitors click on the image below.