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PICAXE-08 ALARM PROJECT
revolution
© copyright 2002 - AXE102 Alarm Student Project Notes Version 1.1
Revolution Education Ltd. Email: [email protected] Web: www.rev-ed.co.uk
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Supported by:
D
IGITAL
S
ENSORS
(S
WITCHES
)
What are switches?
A digital sensor is a simple ‘switch’ type sensor that can only be ‘on’ or ‘off’. If a graph is
drawn of the on-off signals as the switch is pushed it will look like this:
Switches are electronic components that detect movement. There are a large number of
different types of switches e.g:
push switches that detect a momentary 'push'
micro-switches with long levers that detect small movements
tilt-switches that detect jolting
reed-switches that detect a magnet being moved
What are switches used for?
Push switches are commonly used on device like keypads. Micro-switches are used in
burglar alarms to detect if the cover is removed from the alarm box. Reed switches are
used to detect doors and windows being opened and tilt switches are often used to detect
movement in devices such as toys, hair-dryers and tool-box alarms.
Switch Symbols.
The symbols for a slide switch
and a push switch are shown here.
0V
5V
Time
Volt
age
