Dimmer switches have come a long way since their creation in in the 19th century. They are more efficient and less costly than ever before. But how do they do what they do? Find out as B.K. Electrician Services tell you.

1. [The Magic of Dimmer
Switches]
[by B.K. Electric Services]

2. What is a light switch?
• A light switch turns a light On or Off. That’s it. No freaky filters
or disco options. Just plain ol’ “on” or “off”.

3. What is a dimmer switch?
• A dimmer switch not only turns a light on or off, but it can dim
a room for a romantic date or light it like a spotlight.

4. The Early Dimmer
• The first dimmer was designed and invented by inventor
Granville Woods in 1892 for theater use. These were made
using heavy transformers and resistors.

5. • These early attempts used something called a variable
resistor, which was usually a rheostat.
• Rheostats controlled electrical resistance without interrupting
the flow of current.

6. • These variable resistors had a loop of resisting material and
two contact arms (one stationary, one moving).
• The brightness of the light depended on how much resistance
the electricity had to travel through.
• Less resistance = brighter light
• A knob turned the contact arm, which was touching the
resisting material.

7. The slinky is the
resistance. The electricity
has to travel through
more resistance to get to
the contact arm. This
means a dim bulb.
The contact arm is
turned to the left now,
which means the
electricity travels less.
This means a brighter
bulb.

8. The Move to Modern Dimmers
• The problem with these old dimmers was that you were still
using the same amount of energy.
• The resistor would heat up and could burn you or your house.
• Sometime in the ‘60s, Lutron produced the first electronic
solid state dimmer.
• Electronic and solid-state components mean smaller, lighter
dimmers that could be used in the home.

9. The Modern Dimmer
• Today’s dimmer switches interrupt the circuit by rapidly
shutting it off.
• The modern dimmer uses alternating current (AC).
• AC moves in a sine wave, moving up, then down in a cycle.
Two cycles of a sine wave.

10. • AC moves at 60 cycles per second.
• Modern dimmers trim these waves by interrupting the circuit.
• One cycle is cut twice or about 120 times per second.
• If sine waves were going to a club, their purses would be the
parts cut off.
Sorry ladies. The purses
stay up front.

11. Basically…
• That is the gist of how modern dimmers work.
• The brightness of the light depends on how fast the dimmer
turns the circuit back on.
• Modern dimmers don’t heat up as much as their
predecessors.
• Less energy is wasted and the electricity bills are kept low.

12. Resources
• Want to know more? Visit these sites
– howstuffworks.com
– Bkelectricservices.com/electrical-outlets-switches-and-dimmers
• Need a dimmer installed? Contact B.K. Electric Services
– (310) 430-2300
– Visit us at www.bkelectricservices.com/