Download Schematic Symbols - CTE-Auto

Schematic Symbols
The Key to Understanding
Wiring Diagrams
Battery
Supplies a Direct Current (DC) source
Resistor
Resistors impede the flow of electricity
SPST Switch
Opens (off) or closes (on) an electrical circuit
Light Bulb
Converts electricity into light
Fuse
Only allows a predetermined amount of current (AMPS) to pass
through and if that amount is exceeded it will melt in half (open)
Capacitor
Blocks Direct Current (DC) flow, but allows
Alternating Current (AC) to pass through
Diode/Rectifier
Allows current to flow through only one direction
Transistor
A solid-state electronic device that is used to control the flow of
electricity in electronic equipment and usually consists of a small block
of a semiconductor (as germanium) with at least three electrodes
Motor
Converts electrical energy into motion
Electric Fuel Pump
FP
A motor driven pump, which supplies fuel to the engine
Chassis Ground
Connects the circuit to the metal body or frame of the
vehicle using the body as a conductor in the circuit
Ground
Connects the circuit to the metal body or frame of the
vehicle using the body as a conductor in the circuit
(More commonly used than chassis ground)
Relay
An electromagnetically controlled switch
Electromagnet
Becomes magnetic when Direct Current (DC) is passed through it
Light Emitting Diode
A one-way check valve for electricity that
lights up when current is passing through
Variable Resistor
The resistance to the flow of electricity can be adjusted
Variable Capacitor
A variable capacitor is a capacitor whose capacitance may be intentionally and
repeatedly changed mechanically or electronically. Variable capacitors are often
used in L/C circuits (tuners) to set the resonance frequency, e.g. to tune a radio
(therefore they are sometimes called tuning capacitors)
Transformer/Coil
The secondary induced voltage VS
is scaled from the primary VP by a
factor ideally equal to the ratio of
the number of turns of wire in their
respective windings:
By appropriate selection of
the numbers of turns (N), a
transformer thus allows an
alternating voltage to be
stepped up — by making NS
more than NP — or stepped
down, by making it less.
Rotary Switch
Multi-position switch like the one used in the DVOM!
Horn/Speaker
Converts electrical energy into sound