04/22/2019 at 18:26 •
Even though we want to keep this light very simple, customization is also important. People have varying sleep schedules and preferences for dimness. Hopefully we can let the user tune the lights to choose when it should be cool and when it should be warm, and how warm/cool.
We have to choose between Bluetooth and Wi-Fi for this purpose. Currently, we're leaning towards Wi-Fi because we would use Wi-Fi for occupant detection as well (you can look at the previous project log). However, it could prove to be difficult to have both Wi-Fi customization and Wi-Fi as a means of detecting people in a room.
With an ESP32, we can try with both Wi-Fi and Bluetooth to see how it works out. If this becomes more than just a project, we'll try to move to a cheaper and smaller solution.
04/22/2019 at 18:01 •
One feature we would like to have on our light is occupancy detection, but a regular motion sensor will not suffice because of a few problems:
- We want the light to be completely self-contained, and a motion sensor on the light itself will constantly 'trip' if the occupant moves around
- Again with the 'trip wire' concept, it will not work with multiple people, pets, or if you trip it without entering
- If we are constantly using the motion sensor to check for moving occupants, someone taking a bath or shower may be too far or moving too little to be detected.
Obviously a Bluetooth device in the light to detect mobile devices are not optimal because you don't always bring your phone to the bathroom and we don't want to inconvenience the user.
After some research, we have come to the conclusion that using Wi-Fi as a radar is the best solution. By transmitting frequencies and analyzing them when they return to the device, we can see if there is continuous change and detect if something in the room is moving.
04/22/2019 at 17:47 •
Most LED fixtures (including the one we chose) come with warm lights included; probably because it's safest: they replace incandescent (so warm) lights and it's probably better to not have enough blue when needed (morning/day) than too much when not wanted (evenings). Safer!
So off we go to eBay to find some cool lights that we can somehow control as needed.
Item 561939729133 looks promising; should be bright (10W) and comes in cool/cold white (6000-6500K, interesting how the color has a temperature in Kelvin, and the higher the number the cooler it is :-).
I also like the form factor, it should fit nicely in/on our cylindrical diffusers; let's see if it would, as it's 10mm by 200mm (0.4" x 7.9")
The original light we chose from Walmart is only available online so we can't see it before we buy it. We don't like that so we chose a similar one at Home Depot, the "Home Decorators Collection 2-Light Integrated LED Vanity Fixture in Brushed Nickel with Frosted White Glass Shade" SKU 1001018658. Looks about the same and should be available to see/buy in store.
Dimensions are not clear online, so I measure/calculate/approximate that each difuser side is about 8.4" long (if the longest dimension they show as height at 20.47" is in fact the length.
So the LED COB (Chip On Board; means there are many LED chips nicely assembled one one board) would just about fit but we should actually measure it in the store.
Another problem we may have is cooling of the COB but this form factor should be easiest because of the high surface/power ratio. More concentrated lights would more likely need cooling.
We stop here for now, we need to look at the fixture.
04/18/2019 at 01:31 •
I (Cat) will be working on the hardware of our solution. To make things easier I'll start by looking for a suitable off-the-shelf light fixture that I can modify to turn into our first prototype even if it will not be everything the final product is supposed to be.
Which brings up the requirements we'd like to meet:
- Have at least two sources of light: One cold (high blue content) for stimulating morning/daytime light and one warm (low blue) for evenings, that could also become a night-light just by dimming very low.
- Sensor(s) to turn the light on/off as needed. This may get complex as somebody taking a bath/shower may not be detected by an infrared sensor pointing forward. We have to find a solution.
- Some interface to set clock and other values (how dim the night-light, for example). This could be done with Bluetooth and an app but we'd like to find a way for less technical people.
- I'd like the light to be bright but not shine directly into one's eyes, so the custom/final design will include a reflector that will make the light indirect for most people.
On to finding a light to buy to modify.
After a lot of searching online stores like Home Depot, Wayfair, Walmart and some specialist stores we found something we like and think is both classy and modern, at Walmart.
The "Gymax 2-Light LED Vanity Fixture Polished Chrome Wall Sconces Lighting Bathroom".
It includes two E26 LED light-bulbs that might not be exactly what we want if we need space for extra LEDs but would be convenient if we found an easy (for non-techie people) way to adjust tunable (can change color or at least color temperature) light-bulbs like the Philips Hue or others.
Anyway, we'll start with this one for now. The pictures are based on it, and show the main idea.