Three Terminal Devices

Three Terminal Devices

1. BJT2.FET3.UJT

Three Terminal Devices- BJTBJT – NPN - BC 107, BC 108 , BC 109

PNP – SL100 and SK100

Emitter

Base

Collector

Three Terminal Devices- BJTBJT – BC548

BC548

EmitterBase

Collector

Three Terminal Devices- BJT

Three Terminal Devices- BJTTesting of BJT using MultimeterSet the Dial to Continuity Tester

PNP BJT:black lead to base, red lead to collector, result = 675black lead to base, red lead to emitter, result = 688

red lead to base, black lead to collector, result = OL = No conductionred lead to base, black lead to emitter, result = OL = No conduction

black lead to emitter, red lead to collector, result = OL = No conductionred lead to emitter, black lead to collector, result = OL = No conduction

Three Terminal Devices- BJTTesting of BJT using MultimeterSet the Dial to Continuity Tester

NPN BJT:black lead to base, red lead to collector, result = OL = No conductionblack lead to base, red lead to emitter, result = OL = No conduction

red lead to base, black lead to collector, result = 600 – 700 vred lead to base, black lead to emitter, result = 600 – 700 v

black lead to emitter, red lead to collector, result = OL = No conductionred lead to emitter, black lead to collector, result = OL = No conduction

Three Terminal Devices- BJT

Applications of BJT•Amplifiers•Switches

Three Terminal Devices- FETFET – JFET – BFW10

Three Terminal Devices- FETFET – JFET – BFW10

S - SourceD- DrainG - GateB - Body or Casing

Three Terminal Devices- FETFET – MOSFET – IRF540

Gate

Drain

Source

Three Terminal Devices- FETJFET – Testing Using Multimeter

1. Connect the negative lead to gate and positive lead to source . Next connect the negative lead to gate and

positive lead to drain. Both the connections should show high resistance.

2. Connect the positive lead to gate and negative lead to source . Next connect the positive lead to gate and negative lead to drain. Both the connections should

show high resistance.

Three Terminal Devices- FET

Three Terminal Devices- FET

Applications of FET•Low Noise Amplifier

•Buffer Amplifier•Analog Switch•Chopper circuit

Three Terminal Devices- UJT

UJT – 2N2646Lead Identification

E- EmitterB1, B2 - Base

Three Terminal Devices- UJT

Testing Using Multimeter1) With a Digital Multimeter, set in the

Ohms position, read the resistance between the Base 1 and Base 2; then

reverse the meter-leads and take another reading. Regardless of the meter-lead

polarity the measured resistance should approximately be equal (high resistance).

2) Now connect the negative (-) lead of the ohmmeter to the emitter of the UJT. With the positive (+) lead, measure the

resistance from the emitter to Base 1 and then from the emitter to base 2. Both

readings should indicate high resistance and about equal to each other.

3) Exchange the negative lead to the emitter with the positive lead. Measure

with the negative lead the resistance between emitter and Base 1 and from

Base 2 to emitter. Both readings should show low resistance and about equal to

each other

Three Terminal Devices- UJT

UJT – 2N2646Characteristics

Three Terminal Devices- UJT

UJT – 2N2646Applications

relaxation oscillatorto measure magnetic flux