Lamp brightness control - dimmer

[kjh]

For a proof-of-concept project, I need to simulate daylight for day and year cycles. For this purpose, incandescent lamps are OK. Specifically, ten 40W bulbs (~3.5 amps total). They will be off during 'night' and full brightness at 'noon on June 21' and somwhere in between during other 'daylight' hours. So what I think I need is a PC controlled dimmer and a program with two loops one for the day and one for the year.

I searched and found DMX-512 controlled dimmers used to control stage lighting made by Leviton and others. Seems like it would work. Also found some info about rs-232 to DMX-512 conversion and found some manufactured converters but they are pricey.

I have a Compact Fieldpoint system.

Any suggestions of a better way to make a software controlled dimmer? Or if not any guidance regarding the approach outlined above?

Thanks in advance.

Kevin

[johnsold]

Kevin,

There are X-10 controllers which have computer interfaces and lamp dimming capabilities.  See x10.com   The web site is a bit flashy, but prices are reasonable.  There are other vendors as well.

I might not use this for a long term, high reliability project, but for proof of concept it should be OK.  I have some X-10 switches which tend to fail in a year or less. (Not a computer controlled system.)

Lynn 

[AnalogKid2DigitalMan]

One method would be to generate a PWM signal to control a solid state relay. You would modulate how long the relay is on for one cycle of the 60Hz (or 50Hz) power. This is basically how a manual light dimmer works.

-AK2DM

[kjh]

Do you think it might burn out the relay? I think manual dimmers use an scr?

[johnsold]

Solid state relays use SCRs, TRIACs, or FETs so burnout should not be a problem.  Zero crossing switching SSRs might produce significant (and annoying) flicker so avoid them.

Lynn