In response to “X10 Problem”
in the March ‘08 issue, the effect
that Mr. Mode is experiencing is
not caused by a defective X10
appliance module. It is caused by
the way the module was designed.
Keep in mind this is an appliance
module. There are challenges
when trying to use it to control a
compact fluorescent lamp.
These modules have a feature
called local control. It provides a
convenient way of turning on the
appliance without using the
remote control. Let’s say you have
a radio connected to the module.
You are standing at the radio and
want to turn it on but you don’t
have a remote control. All you
have to do is shut the radio off
with the radio’s power switch and
turn it back on. The module will
sense that the load went away and
came back and will turn on the
power to the load.
CFLs confuse the module. They
draw too little current when they
are off. Sometimes when you use
an appliance module to turn off a
CFL, the module will turn right
back on again. Also, part of the
load sensing circuitry has a series
resistor and parallel capacitor. This
creates an old familiar circuit: the
neon relaxation oscillator. When
the module is off, the capacitor
charges through the resistor. When
the voltage gets high enough, the
lamp turns on, quickly discharges
the capacitor, and the lamp goes
off. The cycle repeats. That’s why
you will see the CFL flash periodically when it is turned off.
There is a fairly well known
jumper inside the module that you
can cut to disable load sensing.
This will prevent the module from
responding to changes in the load
but it will not disable the relaxation oscillator problem. There is
another modification for this.
To make both modifications
(this is for the newer style AM466
module) do the following: To open
the module, there is one screw
between the power plug prongs.
Be careful you don’t lose the
house and unit code dials; they
will fall out as you pry the case
apart. With the circuit board oriented component side up, with the
power plug prongs on the top and
the load receptacle jack on the bottom, locate and cut the jumper. It
is located to the right of IC pin 9
just below and to the right of the
right (wider) power plug prong. It
is the only jumper on the board.
Next, locate and cut the diode in
the lower left corner of the board.
It is below the relay. It is the only
diode in that location next to a
resistor and a capacitor.
That’s it. Now the appliance
module will to a very fine job of
■ FIGURE 4
controlling CFLs. No blinking, but
no local control.
Response: Thanks for the feedback, Rick. As you can see, I know
zip about X10. Many readers will
be glad to get this information
along with Mr. Mode.
In regards to the circuit to protect a GPS UNIT in the March ‘08
issue, there could be another reason. The GPS processor doesn’t
reset because of the way the ignition switch operates.
During the start phase, the
accessories are turned off. This on-off-on sequence occurring during a
few seconds and poor reset circuitry in the GPS can cause problems.
Mr. Bukowski might need a
power-on delay module that has a
short reset time. These are difficult
to design. The timing element must
be discharged when initially started, and off when it times out and
when the voltage drops suddenly.
Response: Mr. Bukowski was
using the cigarette lighter socket
for power — which I assume is on
all the time, — but your comment
raises the possibility that using the
accessory line from the ignition
switch might solve his problem.