Lesson 3

Prepare and Interpret Technical Drawings

LEARNING OUTCOMES: At the end of this Lesson, you are expected to do the following:

  • LO 1. identify different kinds of technical drawings;

  • LO 2. interpret technical drawing; and

  • LO 3. prepare/ make changes on electrical/ electronic schematics and diagrams.

Definition of Terms

  • AC voltage - a voltage in which the polarity alternates

  • Anode - the positive electrode or terminal of a device. The “P” material of a diode

  • Bridge Rectifier - a circuit using four diodes to provide full-wave rectification. Converts AC voltage to a pulsating DC voltage

  • Calibration – used to adjust the correct value of a reading with comparison to a standard value

  • Color Code - set of colors used to indicate value of a component

  • DC Power Supply - Set of colors used to indicate value of a component

  • Diode - a two terminal device that conducts in only one direction

  • Full Wave Rectifier - the rectifier that makes use of the full ac wave in both positive and negative half cycles

  • Fuse - a device in the current path that melts or breaks when current protective exceeds a predetermined maximum value

  • Half Wave Rectifier - a diode rectifier that converts AC to pulsating DC by eliminating either the negative or positive alternation of each input AC cycle

  • Leakage - small undesirable flow of current through an insulator or dielectric

  • Light Emitting Diode - a semiconductor diode that converts electric energy into electromagnetic radiation at a visible and near infrared frequencies when its PN junction is forward bias

  • Output - terminal at which a component, circuit or piece of equipment delivers current, voltage or power

  • Power Supply - electrical equipment used to deliver either AC or DC voltage

  • Primary - first winding of a transformer winding that is connected to the source as opposed to secondary which is a winding connected to a load

  • PCB - insulating board containing conductive tracks for circuit connections

  • Rectification - process that converts alternating current to direct current

  • Rectifier - diode circuit that converts AC to pulsating DC

  • Regulated Power Supply - power supply that maintains a constant output voltage under changing load condition

  • Rotary Switch - electromechanical device that has a rotating shaft connected to one terminal capable of making, breaking a connection to one or more other terminals

  • Schematic Diagram - illustration of an electrical or electronic circuit with the components represented by their symbol

  • Secondary - output winding of a transformer winding that is connected to a load

  • Short Circuit - also called a short. Low resistance connection between two points in a circuit typically causing excessive current

  • Solder - metallic alloy used to join two metal surfaces

  • Soldering Iron - tool with an internal heating element used to heat surfaces being soldered to the point where the solder becomes molten

  • Substrate - mechanical insulating support upon which a device is fabricated

  • Switch - electrical device having two states, ON (closed) or OFF (open)

  • Test - sequence of operations intended to verify the correct operation or malfunctioning of a piece of equipment or system

  • Transformer - inductor with two or more windings

  • Troubleshooting - systematic approach to locate the cause of a fault in an electronic circuit or system

  • Volt-Ohm-Milliammeter - known as a multitester. A test equipment used to check AC, DC voltages, current in a circuit and resistance of any components out of the circuit