WHAT ARE THE TYPES OF SWITCH?
(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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