Contents
Vol.35, No.5
May 2022
19 All About Heat Pipes
Air Quality Sensors
page 70
Heat pipes, vapour chambers and thermosiphons are two-phase cooling
(or heating) devices that are used to efficiently transfer heat. They are
simple and inexpensive, commonly used on heatsinks in computers, greatly
enhancing their performance.
By Dr David Maddison
Thermal management
30 The History of Transistors, Pt3
In this final instalment, we take an in-depth look at how bipolar junction
transistors (BJTs) and both main types of field-effect transistors (JFETs
and Mosfets) work at a fundamental level. There’s also a small section
explaining the many different numbering schemes used for transistors.
By Ian Batty
Semiconductors
70 Air Quality Sensors
OUR OW
LD Y
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PAGE 76
Many new air quality sensor modules have been appearing on the market,
some being surprisingly inexpensive. Here’s a quick rundown on what they
do and how they work. Sensor types covered in this article include MOS,
NDIR, PAS and PMC.
By Jim Rowe
Low-cost modules
43 AM-FM DDS Signal Generator
This Precision DDS Signal Generator has an output frequency of 100kHz to
75MHz in 1Hz steps (with ±0.1Hz accuracy after calibration). It runs from a
5V, 140mA supply and has low RF leakage.
By Charles Kosina
Test equipment project
61 500W Power Amplifier, Part 2
This month we cover the assembly instructions for the Amplifier module
PCB, which forms the largest single section of the project. We also provide
some tips on how to wind the output filter inductor.
By John Clarke
Audio project
76 Slot Machine
Real slot machines are an easy way to lose your money, so why not build
your own! This Slot Machine has colour graphics and sound, and while it
uses coins to play, you can get them back when you’re finished playing. The
project is based on the Micromite Plus BackPack.
By Gianni Palotti
Game project
2
Editorial Viewpoint
4
Mailbag
85
Serviceman’s Log
97
Subscriptions
98
Circuit Notebook
1. Simple stereo microphone
2. A simple wireless charger
3. Li-ion battery reconditioner
4. Motion-triggered ESP32 WiFi camera
102
Vintage Radio
92 Oatley LED Lighting & Driver Kits
106
Online Shop
Oatley has four low-cost, high-brightness LED kits which can be driven
from the same general-purpose LED Driver via a 12V DC source. The LEDs
supplied with the kits include one of: two 12W floodlights; two 0.6m 8W
tubes; two 1.2m 18W tubes; or four 60W LED lamps.
By John Clarke
Lighting project
108
Ask Silicon Chip
111
Market Centre
112
Advertising Index
Calstan 559M2 superhet by Fred Lever
