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Re: 3-way lamp problem



On Tuesday, May 6, 2003, at 22:50 US/Eastern, Michael Edmiston wrote:

Unfortunately, I think this means your triac was destroyed when the
bulb
burned out. This is not an uncommon occurrence with light bulb
circuits
in which the bulb is powered through a triac.

The term "triac" seems familiar, but I'm not sure where I've heard it
before.

Regardless of whether it is a touch control or a continuous dimmer, you
might be able to replace the triac. It is a three-pin device that is
most often in the TO220 type of package. There might be numbers on it
that will lead you to a exact replacement. Or, an electric repair
handy-person can probably find a suitable replacement, In a regular
dimmer switch it is hardly worth the cost to repair it unless you do it
yourself for fun. The touch control might be the same situation
depending on the price to replace it.


I'll look, but the whole thing cost all of $15 as I recall. The shade
is made of glass, and I kinda hate to throw it out.

BTW, the way the touch control works is by monitoring the "noise" level
on the touch surface, treating the touch surface as an antenna. The
noise is rectified and integrated with a capacitor and discharge
resistor having appropriate time constant. When you touch the object,
the noise level shoots up because you are an extra antenna. The
circuitry detects this change in noise level and the logic portion of
the circuit toggles the triac into the next sequential duty cycle the
unit it programmed for. The integration feature plus detection of the
change of noise-level allows this to work effectively in different
levels of noisy environment. However, if you touch it too long, it
readjusts to the noise level with you touching it. If you then release
it and touch it again right away, it won't recognize the second (and
subsequent) touches until you stop touching it for long enough for it
to
readjust to the ambient noise level.


Very interesting (and a little complicated ;-) )

Cheers,
Joe Heafner