Contents
Vol.31, No.5; May 2018
SILICON
CHIP
www.siliconchip.com.au
Features & Reviews
14 Drone Air Taxis – Autonomous, Pilotless and Soon!
Already trialling in several countries, you’ll soon be able to call up a pilotless
drone taxi from your smartphone. Fares are projected to be not much more
than street taxis but there will be no traffic hang-ups! – by David Maddison
24 Tiny capsule measures, radios your gut gas data
Medical specialists need to know what gases are in your gut – but they are
loathe to operate. Now researchers in Australia have come up with a capsule
that measures gases and radios the info in real time – by Ross Tester
43 LTspice Simulation: Analysing/Optimising Audio Circuits
Continuing our occasional tutorial series to help you understand the very
versatile LTspice simulation software. It’s still available (free!) from new owners,
Analog Devices – by Nicholas Vinen
82 El Cheapo Modules 16: 35-4400MHz frequency generator
Based on the ADF4351 PLL, this <$30 module can produce a signal from
35MHz to 4.4GHz with crystal accuracy. It can even be used as a sweep
generator – by Jim Rowe
Constructional Projects
28 800W (+) Uninterruptible Power Supply (UPS)
One of our most exciting projects ever: a build-it-yourself UPS which we believe
isn’t as good as commercial models . . . it’s much better! And if you need even
more grunt, this design allows it – by Duraid Madina and Tim Blythman
36 Multi-use Frequency Switch
Some Drone “Taxis” are still
figments of their proponents’
imagination – but some are
already in testing phase – Page 14
Tiny capsules
pass through
the gut, reading
and sending gas
data as they go
– Page 24
Suffer from blackouts in your office
or home? You need a UPS to ensure
you don’t lose
valuable data.
It’s also the
answer to
maintaining
power after a
disaster – Page 28
If you need something controlled when it exceeds a certain frequency – up or
down – this superb circuit will do it. Anything that produces a frequency (or can
have a sensor fitted) can be switched – by John Clarke
57 USB Port Protector – just in case!
We thought we’d fried a laptop when something managed to drop onto the
exposed USB port components. We were lucky – but made up this low cost,
mini PCB to guard against “oopses” in the future! – by Nicholas Vinen
70 12V Battery Balancer
12V batteries in series need careful attention to charging if you’re expecting a
long life. This little balancer does it automatically for you and you can even use
them in parallel for extra power handling – by Nicholas Vinen
Your Favourite Columns
63 Serviceman’s Log
I reckon servicemen are cursed – by Dave Thompson
76 Circuit Notebook
(1) 20V, 2.5A adjustable power supply with current limiting
(2) A personal “speedometer” for joggers
(3) Sunset switch to discourage possums and other night visitors!
(4) Adjustable audio low-pass filter
90 Vintage Radio
Zenith Royal 500 “Owl Eye” AM Radio – by Dr Hugo Holden
Everything Else!
2 Editorial Viewpoint
Feedback
88 Product Showcase
94 SILICON CHIP Online Shop
4 Mailbag – Your
siliconchip.com.au
96
103
104
104
Ask SILICON CHIP
Market Centre
Advertising Index
Notes and Errata
Switch just about any
device if its output
frequency goes above
or below limits which
you set – Page 36.
USB ports can
be fried if
you’re not
careful
(we know!!!).
Be safe with this low-cost
USB Port Protector – Page 57
You can’t simply
charge 12V
batteries in
series as you
would a single
battery – you
need a battery
balancer to ensure
they don’t get out of
balance – Page 70
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