outgoing wires. When the switch is in one position, the incoming wire is
connected to the first of the outgoing wires. When the switch is in the
other position, the incoming wire is connected to the second of the out-
going wires. (If you have a different need and this is the type of switch
you happen to have in your parts bin, you can use just two lugs to make
it work as an SPST.)
DPDT (double-pole, double-throw):This kind of switch has six lugs to
which you can solder wires. These lugs can be attached to two incoming
wires and four outgoing wires. When you flip this switch, you simply
switch each incoming wire between two of the outgoing wires. We use
this type of switch in a relay in Chapter 13 to switch control of the
motors from one type of sensor to another.As if switches didn’t have enough names, they are also referred to by the
method used to change their state from open to closed. See Figure 3-8 to see
the different types.Toggle switch:This switch gets its name from the fact that you flip a
lever to turn it on and flip it back to turn it off.
Pushbutton on/off switch:Every time you push this button, it changes
from on to off or vice versa.Figure 3-7:
Three types
of switches
from left to
right: SPST,
SPDT, and
DPDT.46 Part I: Project Prep