Component Symbols&

Information

Prof. Dr. Moustafa M. MohamedVice Dean, Faculty of Allied Medical Science,

Pharos University in Alexandria

Resistors

• Resistors – An electrical component that opposes or resists the flow of current.

• Values in Ohms (units of resistance) color coded or military specification coded.

K = kilo = 103

M = mega = 106 m = milli = 10-3

Resistors (cont.)

Lead Styles• Axial

• Radial

• I.C. (SIP and DIP)

• Surface Mount

Resistors (cont.)

Types• Carbon Composition – Fixed• Carbon Film - Fixed• Metal Film – Fixed• Wire Wound – Fixed or variable

Resistors (cont.)

Graphic Symbols• Fixed – Zig Zag with 3 points on top and bottom, with

60º angle between zigs, 1/8 to 3/16” tall.

• Variable – Rotary, slide, tapped, switched

• Reference Designation = R

Potentiometer

General – (Rotary, slide, tapped,

switched)

Rheostat

– Used to control current flow.

Capacitors

• Capacitors – A component that stores electrical energy between conductive plates separated by a dielectric insulation material.

• Values in Farads (unit of storage) and working voltage lettered on the body.– μ = micro = 10-6

– n = nano = 10-9

– p = pico = 10-12

Capacitors (cont.)

Types• Electrolytic – fixed – polarized• Tantalum – fixed – polarized• Paper – fixed – nonpolarized• Mica – fixed – nonpolarized• Ceramic – fixed – nonpolarized• Air – variable - nonpolarized

Capacitors (cont.)

Lead Styles• Axial

• Radial

• Surface mount

Capacitors (cont.)

Graphic Symbols

• Nonpolar fixed

• Variable

• Polar Fixed

• Reference Designation = C

+

•Used for coupling /passing AC signals and filtering frequencies (tuning, crossovers)

•Used for storing energy in DC applications (power supplies, filters)•Used for passing AC signals

Inductors

• Inductors – Component that stores electrical energy in the form of a magnetic field. Consists of a coil of wire wrapped around a core of air or magnetic material.

• Also known as – Induction coils, coils, or chokes• Values in Henries (units of storage) color coded or

lettered– m = milli = 10-3

Inductors (cont.)

Types• Air Core – Fixed• Iron Core – Fixed and Adjustable• Ceramic Core – Fixed• Toroidal Core - Fixed

Inductors (cont.)

Lead Styles• Wire Lead

• PC Mount

• Eye Terminal

Inductors (cont.)

Graphic Symbols

Preferred

Iron Ceramic

Adjustable

•Used in filtering and tuning circuits•Reference Designation = L

Transformers

• Transformers – Two inductors constructed side by side with no electrical connection between them. Used to transform energy from one side of the device to the other.– Values in volts, amps, primary (input) and

secondary (output), labeled on units

Transformers (cont.)

Types• Primary-Secondary Ratio

– 1:1 isolation style– Step-up– Step-down– Centertapped– Multitapped– Air core – fixed output– Iron core

• Fixed output• Adjustable outputs• Multitapped outputs

– Ceramic core– fixed output

Transformers (cont.)

Lead Styles• Wire Lead

• PC Mount

• Eye Terminal

Transformers (cont.)

Graphic Symbols• Air Core

• Iron Core

• Iron Adjustable

• Iron Multitapped

• Used for power supplies• Reference Designation = T

Diodes

• Diodes – Semiconductor component that allows current to flow in only one direction. It is also used to regulate voltage and emit light.– Values rated in current flow and voltage threshold

and recovery time.

Diodes (cont.)

Types

• Rectifier• Zener• Tunnel• LED• LCD• Laser• Photosensitive

• Standard Part Numbers -1NXX – 1NXXXX

Diodes (cont.)

Lead Styles• Axial• Radial• Stud• Surface Mount

Diodes (cont.)

Graphic Symbols• Rectifier/Small signal• Zener• Tunnel• LED• Photosensitive

• Reference Designation– CR, LED, DS, PSD

Assignment

State the functions of Capacitor and mention 3 different types of it.