2nd session of R&A Transistors & couplers

Agenda T ransistors as switch. T ransistor testing. O pt couplers. R elays. S imulation with Proteus 7 professional program.

Transistor working theory Consist of two diodes back to back. By controlling states of the two diodes, we can control the switching of the transistor (ON-Off). Look at this program to get the idea !!!!

Transistor OFF state

Transistor ON state

Transistor testing

Opt Couplers Opt couplers make an isolation between interfaces of two circuits. typically consist of a gallium arsenide LED (light-emitting diode) and an optical receiver such As phototransistor or light-triggered diac. The two are separated by a transparent barrier which blocks any electrical current flow between the two, but does allow The passage of light.

(AC/DC) Isolation

DC/DC Converter

6 Pins Package

8 Pins Package

Relays An electromechanical or solid-state device operated by variations in the input which, in turn, operate or control other devices connected to the output. They are used in a wide variety of applications throughout industry, such as in telephone exchanges, digital computers, motor and sequencing controls, and automation systems. Bins configuration (No,Nc,C,Coil).

Simple circuit

Relays -5 Pins

(DPDT) Relays -8 Pins

Controlling Motor Direction

Question ???!!!!! W hen you will use Relay instead of Opt coupler in your application and vise versa??!!!

Simulation Proteus 7 Program

Introduced by E ng. Mustafa Ahmed Hemdan. C hairman of Robotics &Automation Chapter C ommunications & Electronics department. E -mail: M ob: O ur blog : O ur group on facebook : R obotics & Automation Chapter