(a) Push-button.
These are found on calculators,
telephones, electronic games and most equipment with a digital
display.
(b) Rotary.
These are switches controlled by a
knob, and are turned instead of moved up and down. Figure 2 shows the
rear of such a switch and its circuit symbol.
The commoner types of rotary switch
are: 1-pole, 12-way; 2-pole, 6-way; 3-pole, 4-way; 4-pole, 3-way;
6-pole, 2-way. All these switches have 12 click positions, as you may
have guessed, but each one comes with an adjustable end-stop so that
you can set the correct number of ways according to the contacts on
the switch.
(c) Slide.
This switch is common on the cheaper
types of radio, mainly as an ON/OFF or band-changing switch. They are
not very rugged, but are small and cheap to produce. Very small types
are manufactured for use on PCBs.
(d) Toggle.
Available as two-way types or
three-way, with a centre-off position. Can be manufactured to handle
very high currents.
(e) Micro-switch.
These are devices which are usually
operated indirectly, such as when the cover is removed from a
high-voltage power supply, or when the door of a fridge is opened.
The ‘micro’ part of the name
doesn’t refer to the size of the switch, but to the small movement
that is required to activate it.
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