INSTEON Ficker fix -- internal or external choke; was Re: I think they've done it again.

[Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Sun, 25 Jun 2006 12:00:22 -0400, Marc F Hult
<MFHult@xxxxxxxxxxxxxxxxxxxxx> wrote in message
<1f7t92ll7oa28ospsqhfbm3bdvmhqe5nco@xxxxxxx>:

>Mike from INSTEON wrote in
>http://www.techmall.com/post.asp?method=ReplyQuote&REPLY_ID=636&TOPIC_ID=180&FORUM_ID=9
>
>	"The component that is in question is the choke coil. Repeated
>	INSTEON signals generated by the dimmer or controller were getting
>	 into the triac and causing the flicker. We have increased the value
>	 of the choke coil to attenuate the INSTEON signals that go into the
>	 triac. "
>
>
>There are two inductors in an ICON dimmer with an MCU marked "GL2476D BETA"
>with stick-on label. They look just like those on the other model INSTEON
>dimmers I have.
>
>The large inductor (choke) is in series with the red AC [output]lead and
>consists in 4 turns of 14AWG on a ~15 mm diameter green toroid and has an
>inductance of ~18 uH (measured at 120 hz and 1000hz with an EXTECH LCR
>meter). The other terminal of the inductor is connected directly to the
>input of the TRIAC.
>
>In contrast, the choke on an X10 WS467 is about 45 turns of ~16 AWG on a
>25mm long ferrite rod and measures  44 uH. This construction, size and
>inductance is typical of residential dimmers.
>
>"Specification grade" (architectural grade) dimmers have much larger
>inductors. This is one of the inherent advantages of centralized dimmers
>over wall-mounted dimmers because there is no practical limit to the size
>of the inductors in a centralized dimming panel.
>
>(The ICON dimmer also has another, low-current inductor in series with a
>diode near the coupling transformer.)
>
>If, as it appears, the problem is with the high-current [output] choke and
>can be solved by doubling the inductance, more turns on the inductor would
>do the trick if that doesn't cause the inductor to saturate. But if a
>physically larger inductor is needed, space will be a problem. The INSTEON
>dimmer cases are/can be made shallower than most other dimmers in part
>because the choke is smaller.
>
>Because the response from INSTEON implied (to me at least, reading between
>the lines) that an add-on choke might resolve the flicker problem. However
>there isn't room for an add-on choke ("Lamp debuzzing coil") such as those
>sold by Lutron and others in all but the largest switch boxes.

I received a new V2 dimmer from Smarthome and conclude that the fix that
SmartLabs has put in place consists in increasing the number of turns of the
largest inductor ( ~T68 =~16mm =~ 0.68" outside diameter toroid core) from 4
to 12 turns as I noted above. The color of the toroid core (green) has not
changed, so it doesn't seem that they changed the core's composition. (ABIK,
there is no standard color code for composition that is consistent between
manufacturers.) As I also noted above, this makes the inductance comparable
to those in other residential dimmers. The 'fix' also has the minor added
benefit of somewhat reducing noise put on the power line that can then also
be radiated as RF.

Because inductances in series are additive (like resistance) one can
accomplish the same thing by adding a choke _outside_ the dimmer case. This
was apparently contemplated by SmartHome / SmartLabs, but to their credit,
they decided against it --  at least as the only 'fix'.

Of course a home owner could decide to do it herself adding an inductor made
from a core with an OD =>~1" and appropriate material (~$1.50 each at e.g.
http://www.cwsbytemark.com/prices/sendust.php and wound with =>~10 turns of
AWG14 insulated, UL-approved wire (in other words, plain 'ol insulated wire
14 gauge conventionally used in AC wiring) in series with the INSTEON red
(output wire) and connected with wire nuts.

There are also commercially available lamp debuzzing coils (google)  but
these are bulky and relatively expensive and more than what is needed to
solve the flicker problem.

So this tempest-in-a-teapot would seemingly have been avoided if SmartLabs
had put 12 turns on the core to begin with -- although it remains to be
confirmed that this fix definitively eliminates all flicker problems. I have
no INSTEON loads that flicker and haven't tested this.

... Marc
Marc_F_Hult
www.ECOntrol.org