>>>READER-TO-READER QUESTIONS AND ANSWERS
a fixed dollar amount each month. I
want to be able to track it from my
home PC. Any ideas what software I
will need and who sells it for my unit?
I understand that each GPS has its
own identification number so only it
will respond to any query.
#12076 Roy Kneale
[#09072 - September 2007]
I'm looking for a schematic for a
low power wireless switch. Something
simple, using transistors, with a range
of 25-50 feet. Both the transmitter and
receiver should be battery powered
and act as a simple switch.
#1 You can find a schematic for a
low power wireless remote control
switch (maxumum distance of 300
feet using ideal antennas) in an article
by Anthony Caristi, entitled, "Build a
418 MHz Wireless Remote Control,"
in the April 2002 issue of Nuts & Volts.
It provides for a battery powered
receiver and transmitter, as well as AC.
However, it does have digital
circuitry. I think with adjustments you
can limit the range to 25-50 feet.
New York, NY
#2 A radio operated switch is
readily available at hardware outlets
such as Lowe's or Home Depot as
wireless doorbells. Carlton model
RC5110 is battery operated in both
the transmitter and receiver. They are
easily adapted to remote switching.
Net search shows the price as $29.95.
The receiver has a removable
speaker driver that can be replaced to
drive a transistor for whatever. They
are multichannel units, so that several
can be used in the same location.
Three such have been working in my
house for several years now.
Transmitter batteries last nearly a
year when pulsed 40 to 50 times
per day. Four AA NiMH cells in the
receiver last three to four months even
with an LED indicator for OFF/ON
(about 1 mA). The range is more like
60 to 100 ft.
Jack W. Glover
Winter Haven, FL
[#09073 - September 2007]
Our club was vandalized several
times in the last month. I need to put a
video camera at the entry way and turn
on a video recorder using a motion
detector to record anyone who
enters. A commercial motion detector
security camera with a 12 minute
digital video recorder made to look
like a clock is available, but costs $180.
Does anyone make a cheap digital
recorder (recording on an SD or similar
card) that I can trip using a standard
motion detector and which can turn
off when the motion detector sees no
more movement? I can use a pinhole
or similar camera as the video feed so
the video source is not a problem.
Battery operation of the recorder
would be a plus.
#1 Your questions seem to imply
that the camera you were trying at
$180 was expensive. Most people do
not comprehend the cost of good
video equipment. In any event, I have
found a solution for persons who
need something portable, battery
operated, and self-contained. It is
called the, "Recluse" and is considered
a "stealth cam." In a single plastic
container it houses a color camera,
digital video recorder (which will
record on motion), battery, and SD
memory card. It has inputs and
outputs and can be run by the
re-charging transformer that comes
with it. It comes in a nicely packaged
kit with an SD/USB converter so you
can even view or transfer the images
from the SD card into any computer. It
is available at
#2 I recently had a need for a video
recorder to complete a low-cost home
video security system. Originally, I
planned to use a 'spare' PC and plug in
a four channel video capture card
which comes with software. However,
I found a seller on eBay who offered a
brand new, stand-alone four channel
digital video recorder for a 'buy-it-now'
price of only $180 plus shipping.
The catch was these units were sold
without a hard drive.
However, it's easy to install a drive
and adds less than another $100 for a
300-500 GB device. If you already
have a spare drive laying around
(as I did), then there's no additional
cost. The best DVR recording
quality requires about 1 GB per
hour of recording but that storage
requirement could be reduced up to
a factor of 10 by selecting a lower
quality (i.e., more compression) and a
reduced frame rate.
This DVR is specifically designed
for video security applications and
accepts up to four composite video
inputs. It also has the capability to
record a single audio source. The
recorder can be set up to run continuously or on a seven day, hour-to-hour
schedule. In addition, the DVR has
built-in video motion detection
capability that allows custom motion
areas and sensitivity levels for each
camera. Plus, the DVR will accept an
external trigger to initiate recording.
A composite video ouput jack is
provided so you can watch either
the real-time video or play back
previously recorded video. The
recorded video can be transferred to a
PC and saved as an .avi file.
This DVR is network-friendly so
you can actually watch what is going
on from a remote location if there is a
broadband connection available. As
far as I'm concerned, this affordable
device packs in a lot of capability and
compares well to higher-end DVRs I've
seen that cost five times more.
The DVR manufacturer is AV
Tech, Inc. (
model AVC760), and the eBay seller is
kingofgadgets. This DVR, or somthing
similar, is probably available from
other sources but I didn't search any
further. The unit arrived promptly and
has been working just fine.
[#09074 - September 2007]
I would like to use an old 12 inch
B&W monitor (RCA connection a Dell
Optiplex computer) to show text
parameters using this as an EMC CNC
Can I do this? If so — how?
The old CGA standard of 25 years
ago was compatable with B&W
monitors. In fact, the original IBM