64 December 2016
meter swing and the white LED turn on and off; either
charging or emitting light with only a simple transistor
circuit. As they were marveling, I offered a brief description
of the transistor operation in a schematic drawing
describing the details of on-off (Schmitt) switching.
We DID have time to solder at the end. With a circuit
board clamp at a comfortable angle, I used a 15 watt
Weller with the LED lights, put my glasses on describing
the need for a clean, tinned, tip and began soldering a
through-hole PCB describing the process as I soldered each
tiny pad. Would you like to try this? They all did, and I get
teary in how excited they were when they completed their
section of the many other pads. At the end of our class,
the youth librarian shook my arm off in thanks, but I easily
enjoyed it as much. It will be easier than you think. Have
[#9161 - September 2016]
I Got The X10 Blues
My X- 10 home automation gear has been reliable for
years but just recently has become intermittent. Is there a
way to test for what might be interfering with the operation?
#1 X- 10 was developed back in the ‘70s as the first
consumer power line carrier (PLC) home automation
product. While newer and more robust systems are
available, X10 remains popular due to its simplicity and low
cost. Back in the ‘70s, we didn’t have the plethora of wall
warts, PC/printer/monitor power supplies, or CFL and LED
bulbs — all of which tend to either absorb X10 signals or
put noise on the power line or both!
All of these signal suckers and/or noise generators
can swamp the X10 signal resulting in the problems you’re
experiencing. There are filters, amplifier/repeaters, and
couplers to resolve these issues, and I’m happy to report
that after over 30 years of using X10, I’ve been able to
maintain reliable operation even in fairly large homes.
Before adding any of the above devices, the trick is
to identify the source(s) of the problem. At the time the
intermittent problem began, think about what changed in
the house. A new TV, computer, monitor, or phone/tablet
charger? Conversion to CFL or LED bulbs? If any of those
get a yes, try removing them and testing. Plug-in filters will
Does the problem only happen at certain times? For
example, when my in-ground incandescent pool light
burnt out, I replaced it with an LED bulb. When it was on,
it generated sufficient noise to render X10 useless to a
number of locations. The solution was to add a hash choke
in series between the switched wire from the X10 module
and the light. Problem solved.
Another very important consideration is coupling
from one side of the power line to the other. As we all
know, residential service consists of two 120 volt legs (L1
and L2) from the street transformer to the electrical panel
where roughly half the circuits are served by each leg.
Electric ovens, water heaters, and central A/C units are
connected to both legs to provide 240 volt service. If an
X10 controller is plugged into an outlet on L1 and the lamp
module is plugged into an outlet on L2, the signal needs
to find a bridge to get from one leg to the other. That
bridge can be a 240 volt appliance if it’s on, or the street
transformer itself — a long run that attenuates the signal.
The solution is to use a coupler at the electrical
panel to provide a reliable path for the signal to reach
every circuit. The very best solution that will overcome
a multitude of problems is the installation of an XTB-IIR
which is both a coupler and X- 10 signal amplifier. It’s
available both as a kit or fully assembled from www.jvde.
us. Building the kit is within the capabilities of most Nuts
& Volts readers. That site offers a number of solutions and
some great tutorials on X10 troubleshooting. I’ve been
using both their site as a resource and their products for
many years with great success.
#2 I was having the same problem, with flakier and
flakier performance. Some online research indicates that
the problem is the result of the ever-increasing number of
AC power line operated digital devices we use — each of
which can feed noise back into the power line, potentially
causing problems for other devices.
To prevent this, AC power line connections use a lot
of filtering components (inductors and bypass capacitors)
to prevent the digital noise from traveling back into the
AC power line, but the bypass capacitors essentially short
circuit the 120 kHz X- 10 signals so they can’t reach the
devices they are intended to control. It’s time to switch to
Z-wave or one of the other radio-based control systems.
San Gabriel, CA
>>>YOUR ELECTRONICS QUESTIONS ANSWERED HERE BY N&V READERS
FIGURE 1. Just to the right of the white LED junction, between
the 3. 6 volt battery, insert the zero-center galvanometer. A 3-4
ohm shunt between the ± meter connections offered dramatic
visual current direction. Raise or lower shunt resistance as needed.