Hands-On-Physics
IEU Concepts
COMPONENTS
This list is a description of what the various components
do. If you would like more detailed information about how they work, refer
to an electronics textbook.
Switches These make contact between two wires or break contact between
two wires. The spring loaded switches are classified as normally open (NO)
or normally closed (NC). NO switches have the connection open, or broken,
unless the switch is pushed. NC switches have the connection closed unless
the switch is pushed.
Resistors These provide resistance to the flow of electric current.
The larger the resistor, the more opposition to current it provides. In
doing this the resistor reduces the voltage of the electrons passing through
it, and that energy is let off as heat. So an overloaded resistor gets hot,
and can even melt (this is smelly) or burn (even smellier).
Transistors These act as switches which can be turned on and off
electronically. Large amounts of current are controlled by very small currents.
Normally a transistor provides very high resistance between the collector
and the emitter; it allows no current through. However, once there is a
small current through the base to the emitter, the resistance between the
collector and emitter plummets, allowing current to flow.
Bridge Rectifiers These are collections of four diodes. Each diode
allows current to flow in only one direction. The four diodes are put together
so that alternating current, which goes from positive to negative, is only
allowed to oscillate only between zero and a positive number. When the current
goe negative, it is flipped to become positive.
Voltage Regulators These permit only voltages up to a maximum. Any
voltage above the maximum is chopped off and extra energy is dissipated
as heat. Therefore, you should always have a heat sink on a voltage regulator.
Capacitors These store charge (electrons). When the charging voltage
is removed after the capacitor is charged, the capacitor can push the electrons
back through the circuit. This results in smoothing out peaks and valleys
in the voltage. The larger the capacitor, the more charge it can store.
The electrolytic capacitors will POP and be destroyed if they are connected
backwards.
Potentiometer Dimmer switches are potentiometers. Potentiometers
(pots) provide a variable resistance; twisting the shaft changes the resistance
to allow more or less current through. This should control the brightness
of the light bulb, the volume of the buzzer, or the amount of voltage out
of your LVPS.
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