Since my apartment doesn't get enough sun and I don't get enough UV outside in the winter, I want to simulate summer sunlight in my home.
I have a 100W 12V incandescent light bulb. The goal is to create a function of real time to power output to the bulb. If my understanding is correct, slowly raising/lowering the power output to an incandescent bulb would pretty well simulate dawn and dusk, and I'd love for it to be automatic.
So for example, I might program it to start at 5am giving 0% power to the bulb linearly increasing to 100% at 9am, then at 5pm it starts linearly decreasing to 0% by 9pm. But this should all be easily changable, I want to be able to play around with making it perhaps exponential or following some other kind of function, and being able to adjust the times and power ouputs easily.
My first instinct is to read from a real time clock unit into an Arduino and do my logic there. However as an electronics novice, the next part of getting the output from the Arduino and somehow turning that into a same-current modulated-voltage power supply to the bulb is where I think I need help. Is my basic assumption of lower voltage, same current to incandescent globe = dimmer, redder glow even correct? Is there a simpler way to do this?
Lower average voltage. You do that my providing a pulsewidth modulated (PWM) signal to a MOSFET which turns the bulb on/off hundreds of times per second. The bulb can't respond that quickly so it will average out the signal. Lower PWM signal, less voltage, dimmer bulb
I built a "sunrise wake-up system" a long time ago with a different microcontroller. I still use it. I already had a home-automation system so I used that for time-of-day. The part I built just fades-up when power to that outlet comes-on. That could also be done one of those little plug-in timers from the home improvement store.
Sundown/dusk wouldn't be as easy, but you could do something similar with a relay on the timer just to send a "signal" with separate switched power to your dimmer gizmo. That would save you the trouble of including a real time clock, or you could add it later.
At that low voltage it's most likely a halogen bulb, and they can't (shouldn't) be dimmed.
If you do dim them, then the bulb will fail much faster.
There are LED lights (or strips) with cool/warm white in the same LED package. Mix cool/warm to get the colour temperature you want. Search for "CCT LED(strip)". A sunrise/sunset sketch can do the dimming/mixing for you.
Leo..
Considering the bulb is at 3200K, and with my understanding of black body radiation, it should provide a non-negligible amount of UV radiation. I think when people say "incandescent bulbs don't create UV" they are likely referring to the fact that the glass typically encasing the bulb blocks it out. However my bulb has a quartz glass casing that only blocks out the very shortest wavelengths (UV-C radiation).
