untitled

You can think of a DPDT (double-pole double-throw) switchas containing two

SPDT switches that switch in tandem. To see an example of this in action,

visit Chapter 13, where we use DPDT relays to simplify the wiring of our

breadboard.

Schematic variables .............................................................................

Some components are polarized,which means that you have to put them in

the circuit in a particular way. Schematics can identify the polarity of compo-

nents (see Figure 4-5).

AND gate

In Out

OP amp

+ Out

+ Supply

Supply

Battery

Relay

+ +

Diode

Negative

terminal

Negative

terminal

Positive

terminal

Positive

terminal

+

Capacitor

NPN transistor PNP transistor

Figure 4-5:
Common
polarity
symbols.

Chapter 4: Running Down the Skills You Need 63