At 1A, expect to charge and run
your phone without a problem since
most cell phones — even on transmit
— are below 1W output. Refer to:
Phil Karras KE3FL
[#8141 - August 2014]
Audio Mixer Question
I have a rather old audio mixer that
has 1/4" inputs for microphones.
The inputs are labeled "HiZ." I have
microphones I'd like to use, but they
have a three-pin "XLR" style connector.
Do I need some kind of matching
transformer, or can I just use a 1/4"
male plug wired to some of the
contacts on the XLR jack?
#1 For starter, you CANNOT use
a 1/4" male plug wired to an XLR jack.
The 1/4" line is unbalanced, meaning
there is one signal line and a ground.
The XLR line has two signal lines with
opposite and equal signals plus the
ground. Use a RadioShack model
274-016 (or equivalent) A3F XLR jack
to 1/4" plug adapter. This adapter
contains a balance-to-unbalance
(balun) transformer to match the two
lines properly. The balanced line and
High Impedance (HiZ) are both used
to reduce interference on low level
signal lines like microphones.
Tim Brown PhD EE, PE
Honea Path, SC
#2 Yes. You need an adapter to
mate that "unbalanced" (Hi-Z) microphone input to a "balanced" (Low-Z)
microphone. Here are three ideas:
RadioShack sells item #274-016
(you'll need cables to connect the
two ends). Here's the link: www.radio
uctId=2062443. Chances are your
local Shack has it in stock.
Parts Express ( www.partsexpress
.com) sells a similar adapter: www.
If you're handy with a soldering
iron, here's a DIY idea:
www.media-college.com/audio/connection/xlr-jack-mono.html (all necessary parts
are available at RadioShack).
All three methods will do what
you need — just pick the option that's
easiest for you to implement.
[#8142 - August 2014]
Help Identifying an Old Robot
I picked up an old robot chassis at
an estate sale for $25. I have taken
some pictures in the hope someone
might be able to identify the make/
model for me.
I am SO jealous! That is the RB5X
robot made by RB Robotics in 1982.
You can read more about this
awesome robot on my website at
robots/ rb5x.htm or at this other great
site at www.theoldrobots.com/
rb5x.html. I hope you enjoy your very
impressive find! I'm still looking for
one of my own.
[#8143 - August 2014]
iPod Battery Reconditioning
My son has gifted me with his
cast-off iPod Classic 30 gb player.
Unfortunately, the battery life is only
about 15-20 minutes of playing before
it goes dead. Does anyone know of a
way to recondition the battery?
#1 Forget the old battery and buy
a new Lenmar replacement battery for
the iPod Classic 5 G ( 30 Gb) This battery replaces 616-0230 and EC008-2.
Amazon carries them for around
$15. The Portable Rechargeable
Battery Association (PRBA) highly
recommends against using reconditioned lithium-ion batteries, and I
would assume this also applies to
lithium-polymer batteries due to their
propensity for catching fire. I found
one website that advocated a repeated freeze and charge process, but for
$15 I would buy a new known battery
versus trying to resurrect a possibly
Tim Brown PhD EE, PE
Honea Path, SC
#2 The first iPods were famous for
the irreplaceable battery, and they
are extremely hard to open. IFixit
considers the iPod Classic battery
replacement "very difficult," and you
can find some YouTube videos on
opening and replacing the battery if
you dare to do it yourself.
If you wish to continue using your
son's iPod Classic as a portable
music player but don't want to risk
damaging it, consider attaching a
portable external battery. If your iPod
Classic uses a USB cable to charge,
then buy an external USB battery
which can supply five volts and at least
0.85 amps (850 milliamps). Some are
as large as the iPod, so just tape it
back-to-back, and use the shortest
USB cable between them. They are
rechargeable from any other USB
port, and will be useable with smartphones if you desire to retire that iPod.
Raymond J. Ramirez
>>>YOUR ELECTRONICS QUESTIONS ANSWERED HERE BY N&V READERS
Send all questions and answers by email to email@example.com
or via the online form at www.nutsvolts.com/tech-forum
September 2014 95
Hell, there are no rules here
— we're trying to accomplish
Thomas A. Edison