2nd session of R&A Transistors & couplers

Agenda

• Transistors as switch.• Transistor testing.• Opt couplers.• Relays.• Simulation 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!!!!!???

• When you will use Relay instead of Opt coupler in your application and vise versa??!!!

SimulationProteus 7 Program

Thank you

Introduced by• Eng. Mustafa Ahmed Hemdan.• Chairman of Robotics &Automation Chapter• Communications & Electronics department.• E-mail: hemdan@ieee.org• Mob: +20173220460

• Our blog : • http://rastsc.wordpress.com• Our group on facebook :• Robotics & Automation Chapter