Why do 120V dimmers make LV lights flicker?

[epinc]

I know you should match your LV dimmer to the transformer type of the low voltage lighting but why don't 120v dimmers work? How does the LV dimmer work differently than a 120v dimmer?

Thanks

 

[iwire]

I know you should match your LV dimmer to the transformer type of the low voltage lighting but why don't 120v dimmers work? How does the LV dimmer work differently than a 120v dimmer?

Thanks

The diferance is how the standard sine wave is chopped up.

Is the gentle ramp leading the peak of the sine wave or is it following the peak of the sine wave?

The cheaper dimmer lets the voltage ramp down slowly but it rises very fast.

This is fine with incandescents but with transformers it creates continuous high in rush currents.

The transformer will want a slow rise of the voltage but can take a sharp drop off. However those dimmers cost more to make.

Bob

 

[iwire]

Here is a 'normal' sine wave

Now here is the same wave chopped up with a cheaper dimmer

That wave would be tough on a transformer.

Picture it flipped 180 degrees and that would be how the better dimmer would chop up the wave.

 

[ramsy]

With outlets controlled by a dimmer my ZIRCON CF 12 Pro (breaker finder) doesn't work when using the screwshell adapter (checking from the light fixture). I am forced to bypass the dimmer by opening the switch and clamping the energized terminals.

I wonder if any wire tracers can transmit a signal thru these dimmers.

 

[benmin]

There are differances as to how incandescant, magnetic and electronic loads are dimmed. goto http://lutron.com/technical_info/pdf/LutronDimmingBasics.pdf for a good explanation. Usually when I've miss matched the dimmer to the load, I get flickering and humming (worst in LV track heads).


You will not be able to get a circuit tracer to work through a solid state dimmer since it is a one way device and will not allow the signal to get back to the breaker panel.

 

[ramsy]

Many thanks Benmin. I have added that excellent reference to my library.

I now remember, solid state bridge rectifiers covert AC to DC, made from one-way diodes.

However, shouldn't a good wire tracer work with incandescent dimmers, if those are just simple chokes, potentiometers, or rheostats?

 

[benmin]

I work on a lot of Lutron Home works interactive and Radio Ra projects so I can get some good technical/engineering assistance from them. Here is what they say about dimmers and circuit tracers.


> Ben,
>
> Digital dimmers, like the Maestro series, have electronics that are
> powered when the circuit is completed through the load. If they aren't
> powered, the Triac is off which is equivalent to an open circuit. This
> will cause a circuit tracer to not function past the dimmer. With an
> analog dimmer, depending on the tracer the ringing signal may be
> distorted by the switching of the Triac which may cause the
> receiver/tracer to not work. Circuit tracers are excelent
> troubleshooting tools, but, as with most tools, it has its limitations.
>