Vectronics VEC-841K User Manual

Page 6

VEC-841K Owner's Manual

Tunable SSB/CW Audio Filter Kit

Reading Capacitors: Unlike resistors, capacitors no longer use a color code for
value identification. Instead, the value, or a 3-number code, is printed on the
body.

Multilayer

271

(270 pF)

Ceramic Discs

|
|

1uF

35V

104

Electrolytic

1 uF

10 pF = 100
100 pF = 101
1000 pF = 102

.001 uF = 102*

.01 uF = 103
.1 uF = 104

Value Code

102

(.001 uF) (.1 uF)

As with resistors, it's helpful to sort capacitors by type, and then to arrange them
in ascending order of value. Small-value capacitors are characterized in pF (or
pico-Farads), while larger values are labeled in uF (or micro-Farads). The
transition from pF to uF occurs at 1000 pF (or .001 uF)*. Today, most
monolithic and disc-ceramic capacitors are marked with a three-number code.
The first two digits indicate a numerical value, while the last digit indicates a
multiplier (same as resistors).

Electrolytic capacitors are always marked in uF. Electrolytics are polarized
devices and must be oriented correctly during installation. If you become
confused by markings on the case, remember the uncut negative lead is slightly
shorter than the positive lead.

Diodes: Diodes are also polarized devices that must be installed correctly.
Always look for the banded or cathode end when installing, and follow
instructions carefully.

Cathode

Diode

LED

(shorter Lead)

Transistors: If transistors are installed incorrectly, damage may result when
power is applied. Transistors in metal cases have a small tab near the emitter
lead to identify correct positioning. Semiconductors housed in small plastic
cases (TO-92) have an easily-identified flat side to identify mounting orientation.
Many specialized diodes and low-current voltage regulators also use this type
packaging. Larger plastic transistors and voltage regulators use a case backed
with a prominent metal tab to dissipate heat (T-220). Here orientation is
indicated by the positioning of the cooling tab.