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4 July 2015
Reader Questions Answered Here
Topics this month include: a CR18650 battery vs.
cell charging; help with vintage PA amps; and
12 PICAXE Primer
Sharpening Your Tools of Creativity
PICAXE-PC Serial Communications Part 2.
We’ll continue our exploration of hardware serial
communication between a PICAXE and a PC.
18 Open Communication
The Latest in Networking and
Smartwatches Need Communications Too.
The new Apple Watch acts as a peripheral device
to your smartphone by utilizing multiple wireless
links between the two devices.
61 The Ham’s Wireless Workbench
Practical Technology from
the Ham World
All About Ferrite.
Rings, beads, cores ... find out exactly what ferrite
is and what makes it ideal for a variety of uses
68 The Design Cycle
Advanced Techniques for
Building a Multipurpose
Clear your bench and tin your soldering iron.
In this installment, we’re going to scratch build a
multipurpose embedded communications board.
While the soldering iron is cooling down, we’ll fire up
the Microchip XC32 C compiler under MPLABX and
bring our new garage-brewed creation to life.
22 Modify a Kill-A-Watt EZ Power Meter
for Low Voltage Operation
Discover a simple modification that safely powers
the Kill-A-Watt meter for accurate operation in the
low (10%-20%) voltage regime.
■ By Kevin J. O’Connor
26 Beyond the Arduino — Part 5
Please DO interrupt me! This time, take a look at
how to handle interrupts in your Atmel AVR
embedded projects, and how they can make your
projects more efficient and easier to develop.
■ By Andrew Retallack
34 FPGAs for the Hobbyist
This tutorial will get you up and running with
field programmable gate arrays — no prior
■ By Ryan Clarke
40 An Ultra Modern Shortwave Radio
A simple circuit, a USB TV tuner, your computer,
and some powerful (free!) software combine to
make an amazing software defined communications
receiver for around $25.
■ By George R. Steber
46 Reviving a Hi-Fi Classic:
the Harman/Kardon A-401
Stereophonic Control Amplifier
Vintage stereo equipment just has a special sound
and presence that are worth preserving. Follow
along on a recent restoration of a 38 year old amp.
■ By J. W. Koebel
52 Power Sources: The Good, the Bad,
and the Ugly
What you don’t know about your project’s power
source may be the problem. Learn the most
important features you should care about for four
common power sources,
how to measure them,
and what to expect.
■ By Eric Bogatin
Change the World
06 READER FEEDBACK
20 NEW PRODUCTS
74 NV WEBSTORE
78 TECH FORUM
81 AD INDEX