BE Lesson 4: Transistors What are semi-conductor transistors? What’s the primary difference between a bipolar transistor and unijunction transistor? How we can use these transistors. © 2012 C. Rightmyer, Licensed under The MIT OSI License, 20 July 2012

What are transistors? Make:Electronics, Oreilly Publishing, Charles Platt, 2009

Silicon based semiconductor doping Silicon atom with 4 electrons in outer shell Silicon atoms sharing outer electrons Hole Extra electron Silicon crystal with Boron atom Silicon crystal with Phosphorus atom Adapted from Getting Started in Electronics, Master Publishing, Inc., Forrest M. Mims III, 2010

How an NPN type transistor works Practical Electronics for Inventors, McGraw Hill, Paul Scherz, 2007

Symbols and example math for bipolar transistors NPN PNP

BE ckt 4-1. Illustrating current amplification using an NPN bipolar transistor (2N3904). +  volts LED 100  4.7K  LED 2N3904 B C E Adapted from Electronic Kourseware Interactive, Discover Electronics, A8,

BE ckt 4-1. Hook up diagram volts K LED 2N 3904 (face points towards bottom of breadboard) LED c e b

BE ckt 4-2. Measuring current amplification Adapted from Electronic Kourseware Interactive ( LED 100 ohm 100k pot 9 v + ma c e b NPN ohm

BE ckt 4-2. Hookup diagram volts 100 NPN 3904 (faces down on breadboard) LED c e b 100k pot ma

A Programable Unijunction Transistor (PUT)

BE ckt 4-3. A flashing LED circuit using a 2N6017 Programmable Unijunction Transistor (PUT) BE ckt 4-3 Adapted from Make:Electronics, Oreilly Publishing, Charles Platt, k 10 uf 10k 20k R1 R2R3 C1 LED 9V DC

BE ckt 4-3. Hookup diagram + 10 uf c a 82K g 220 LED 10K 20K a = anode c = cathode g = gate Note: Transistor 2N6027 faces down on the breadboard) volts

BE ckt 4-4. The “Blinking” Project

Front of protoboard (ckt 4-4a) 82k = Gray-Red-Orange 10k = Brown-Black-Orange 20k = Red-Black-Orange 220 = Red-Red-Black 10k10k 20k20k This symbol means you are to twist one of the bare Wire leads around the other up close to the bottom of the board. Two turns is enough.

Front of protoboard (ckt 4-4b) 82k = Gray-Red-Orange 10k = Brown-Black-Orange 20k = Red-Black-Orange 220 = Red-Red-Black 10k10k 82 k 20k20k

Front of protoboard (ckt 4-4c) 82k = Gray-Red-Orange 10k = Brown-Black-Orange 20k = Red-Black-Orange 220 = Red-Red-Black 10k10k 82 k 20k20k

Front of protoboard (ckt 4-4d) 82k = Gray-Red-Orange 10k = Brown-Black-Orange 20k = Red-Black-Orange 220 = Red-Red-Black 10k10k 82 k k20k 10 u F + 10k10k 82 k k20k

Front of protoboard (ckt 4-4e) 82k = Gray-Red-Orange 10k = Black-Black-Orange 20k = Red-Black-Orange 220 = Red-Red-Black 10k10k 82 k k20k 10  f +

Completed ckt k = Gray-Red-Orange 10k = Black-Black-Orange 20k = Red-Black-Orange 220 = Red-Red-Black 10k10k 82 k k20k 10  f +