Switches are electromechanical devices. The are used to control the
path of current or energy flow. Power switches are used to turn on and
off loads. The contacts should be robust and have immunity to sparking
and corrosion. Switches for signals need to be gold plated for low
contact resistance and within a sealed enclosure.
Rocker and Plain Rocker DPDT switches are popular in Power Boards and
Extension Boxes for Mains power switching. Both Phase and Neutral lines
are switched ON or OFF. This is not only safe but also reduces sparking.
Pushbutton and Tact switches are common
in circuits with digital controls. Tact is for signal switching. Large
pushbutton switches are used in control panels for Motor and Heater
A Neon bulb should have a resistor is series to make a Neon Lamp. All specs in designer viewpoint.
contacts and fuse contacts can spark badly and cause fire hazards,
periodic examination, service and replacement may be necessary. The
sparking also causes spikes, emi, along with inductors or coils or even
long wires that are wound up in the path of current. This effect
damages smps and electronic systems in its path, if not adequately
The low signal switches do not have the
above problem. Then.. switches that need to control microamps of
current and battery contacts of portable electronics that consume micro
power have a unique problem. A thin oxide layer on the contacts or
thermometric emfs due to electroplating defects can cause bizarre
effects. These contacts must be immune form the environment, sealed,
gold plated and clean. Even a little ammonia gets close to the contacts
could cause problems in signal and power switches.
sunlight, corrosive fluids and exposed or heating electromechanical
contacts in connectors and switches are a designer and service
Nickle Silver Alloys are used in
some contacts of switches, relays and connectors. Beryllium Copper is
used for its Spring action.