Optically isolated light dimmer

[raivo]

Does anyone know of triac-based light dimmer circuit where potentiometer is optically isolataed from mains?

Raivo

 

[IRstuff]

Why in the world would you want to pay for the extra complexity that's not necessary?

TTFN

 

[dumbo]

It seems logical that a remote dimmer would accept IR

 

[IRstuff]

Remote control is not equivalent to optical isolation.

Optical isolation is simply decoupling of the electrical signal through conversion to an optical signal. The isolation occurs within the same package, transmitter and receiver are placed millimeters apart and there is no interaction with ambient lighting.

Remote IR control requires a totally different receiver, since it must deal with the ambient lighting background and must be able to resist a significantly higher level of noise.

In either case, the amount circuitry is substantially higher than a simple rheostat. You now need to control 120Vac signals with digital inputs. Additionally, you'll need some means of converting what is ostensibly an analog input into digital signals.

TTFN

 

[Heydave]

You could use a solid state relay driven with a variable duty cycle oscillator controlled by a pot. To reduce electrical noise, make sure the opto relay uses zero crossing switching. The oscillator frequency should be a frequency that will not harmonize with the mains or the dimmer will be fading in and out.

 

[Chuckles159]

A zero crossing solid state relay is fine for static switching but not suitable for dimming. You cannot have zero crossing switching and phase control at the same time. They are mutually exclusive terms.
I have built loads of optically isolated dimmer and lamp control circuits over the years. However, they are far more complex than a standard dimmemr as a separate low voltage supply is needed for the control side.
If this is a one shot job, just get an X-10 dimmer module and separate X-10 control unit and be done with it. Total cost maybe $30.00.

 

[jimthompson]

Several years ago I designed an optically isolated triac circuit to be used in conjunction with a low voltage control for resturant applications. The product is still being manufactured and sells for several thousand dollars.

 

[bear33]

Check out Crydom PCV series. it needs 0-10 vdc which you can create to input the control signal for dimming. I helped design this product and it works well. If you need some call me 800-879-7918 frank@hbcontrols.com

 

[lyng]

I need to convert 220V mains to 110 V AC I would like to use a phase controller and a triac It is driving a 110V primary of a transformer. Any possible circuits and solutions?

 

[Chuckles159]

220V to 110V with phase control. Only if you want the transformer to buzz like crazy. Transformers do NOT like this and will die an early death. Also, if the triac goes, the full 220V will be applied to the load. This is very likely to happen as the transformer appears as a short to the triac when the magnetic field builds up when the triac comes on part way through the cycle. This will kill a triac much sooner than it might otherwise. If the triac approach worked simply, it is what would be done already as transformers are big, bulky and expensive. I tried the triac approach in the 70's and probably condemned half a ton of transformers to destruction.

By the time you add enough noise filtering to reduce the transformer buzz and kill the EMI, you're up to the cost of doing it right.

Also, don't use the cheap adapters that say they are for heating appliances only. They mean that because all they are is a diode and they apply half wave DC to the load.

When you see things like monitors with 90 to 264V input, they have a switchmode isolated power supply.