Capacitor Selection

What is the selection criteria for capacitors other than their values. Why only polarised capacitors are used in power supply.
Thanks

Posted by mustafapk on 18/02/2005, at 02:31 GMT

Capacitor selection

For polarised capacitors you must check that their 'working voltage' is sufficiently high, it must be at least the supply voltage of the circuit (there are some exceptions, so be guided by the instructions for a project). Unpolarised capacitors have high working voltages (100V for example) so you can ignore this for low voltage circuits. You may need to consider the physical size and lead orientation (axial or radial) too.

Power supplies use polarised capacitors because they need large values for the smoothing capacitors and these are only available polarised. It is difficult to make unpolarised capacitors with a small physical size for values greater than about 1µF.

Further information: www.kpsec.freeuk.com/components/capac.htm

Posted by John Hewes on 20/02/2005, at 17:04 GMT