CAPACITORS CAN STORE A LETHAL
always discharge a capacitor with one hand holding an insulated
the other hand behind your back!!
bleeder resistors that normally drain the capacitor
be defective .... the capacitor will remain charged to
are electrical components that can store and then release electrical
charge that is stored in an electrostatic energy field.
Stud welders in automated manufacturing processes often use the energy
stored in capacitors to melt steel.
> the energy released from large
can be powerful enough to power a spot welder or accelerate a hybrid
> capacitors can be used to
create phase shifts
in inductive circuits AC or to
start rotation of split phase motors
> in power supplies capacitors are used to
(remove certain frequencies)
power and communications circuits
> the predictable times taken to
capacitors make them useful for
timing circuits and oscillators
All capacitors have the same basic construction:
separated by an insulating material called a
- plates are often made of foil that is wrapped around a sheet of
(I once built the tuner for my first
radio from chewing gum wrapper)
- sometimes the dielectric material is
air, paper, oil, tantalum, electrolyte, or other material depending on the
Action > Capacitors store electrical energy as an electrostatic field between the 2 plates when charge is moved from one plate to the other by a difference in voltage.
Capacitors are rated by how much electrical
charge they can store
per volt applied.
where Q = Coulombs
(6.24 x 1018 electrons)
C = FARADS = Q/V
of a balloon. The greater the
pressure the more air
The first few breathes of air are easy the last ones are hard. Air rushes
out of balloon quickly at first. Then slowly later. Apply too much air
pressure to a balloon and it pops.
Substitute voltage for
pressure and electron charge for air and you have capacitor action.
Capacitors are rated as
Farads or 1 trillionth Farad
1000,000 picoFarads = 1 uF
1,000,000 uF = 1 Farad
small disc capacitors for high frequency timing and
(usually no polarity
= 1 microfarad = uF =
= 1 millionth
electrolytic capacitor used everywhere in electronics
(observe polarity band on
- 1 millifarad (mF) = one thousandth (10−3) of a farad or 1000 μF
- 1 microfarad (μF, or MFD in industrial use) = one millionth (10−6) of a farad, or 1000000 pF, or 1000 nF
- 1 nanofarad (nF) = one billionth (10−9) of a farad, or 1000 pF
- 1 picofarad (pF) = one trillionth (10−12) of a farad
1 million microfarads = 1 F
Car audio capacitor used to deliver pulses
of extended bass audio signal to high power speakers during the down beat.
Ever see a car audio system dim the headlights to the bass beat of the
tune. That system needs larger capacitors on the input that can supply
pulses of energy to the amplifier.
The capacitor must charge quickly between
beats and so must have a short Time Constant
Capacitors are rated by the charge
they can store per volt (Farads) AND maximum voltage.
A capacitor that is connected to a voltage that is to high will EXPLODE
with a bang. They can
electrolytic capacitors must be installed with correct polarity or they
can explode!!! Look
for the band (negative electrode).
Tiny trimmer (variable) capacitor used to
fine tune an oscillator or timer circuit
Variable air capacitor used to tune in
High voltage industrial oil dielectric
Ultracaps in Hybrid Cars
Capacitor charge discharge times