Building Lighting control

I've talked about interiors and lighting before, so this is a continuation on that theme. Not all buildings need to be light at the same intensity, and backing off on the intensity could even be a good thing, preventing light from leaking through the exterior plastics.

A solution to this would be to install a potentiometer ("pot" or variable resistor) in series with the light. Turning the pot will allow the lights to brighten or dim as needed. Always install a fixed resistor between the pot and LED in case the pot is turned down to nothing. Multiple LEDs can be connected to a common pot, so the entire building dims at once. As long as there is a fixed resistor before the LED, the one-resistor-per-LED rule is maintained.

The pot really doesn't need to be any bigger than 5K, but sizes up to 25K should be quite usable. If you have larger values, the adjustment may get to be so fiddly that it's difficult to use. In this case, a resistor can be connected in parallel with the pot (one lead goes to the "input" side and the other goes to the "output" side you're using.)

Connecting a resistor in parallel with a pot does two things: It changes the response from linear to logarithmic, which means that as you adjust the pot the change will be quite immediate and then taper off as you approach the fixed resistor's value. The next thing you need to be aware of is this part will no longer attain 0 ohms. When the pot is at 0, the fixed resistor still provides some resistance. The value of the fixed resistors on the LEDs can be adjusted to compensate.

In short, to adjust the light output a potentiometer can be used. Always install fixed resistors in series with LEDs, but the LEDs can be connected together so one pot controls the entire building.