Thursday, July 17, 2025
Homebrew Automated Roller Blackout Blinds
Our slat blinds were still letting in way too much light even when closed tight, so I went back to my original plan of blackout curtains. Initially I had planned to make a pull string to open and close the blackout curtains we already had hanging from a standard curtain rod. But we switched rooms since then, so I was starting from scratch and thought roller blinds might be more reliable. I looked for some to buy--I really did--but all were either too narrow or lacked the exact automation features I needed and were very expensive, so I just made my own.
The hardest part was just finding a tube that was simultaneously long, light, and stiff enough. You can buy aluminum tubing from supply shops, but it's always overkill in the thickness (quite heavy) and super expensive. Finally I found just the thing, masquerading as a pool-net pole at Lowe's for $40:
Technically there are two beautiful, almost-8' foot long, aluminum poles for that price, one inside the other.
A nail-biting moment:
I used the shaft of a broken crossbow bolt as the axel through a roller blade bearing, and stuck some wedges in so I could secure it with a couple of screws:
For the drive train I started with an old tricycle axel, no longer in use since it's been converted to a balance bike:
The coupling between the motor and the shaft is the same surgical tubing I used before, but with a printed compression cuff with slip-on cover that holds it snug and straight. There is no hard contact to the motor anywhere, which is vital as any time the motor touches anything hard you can hear a hum or buzz:
Some simple wall brackets which the whole assembly just drops into:
For the electronics I gutted the previous blinds turner, which had a mis-used magnetic rotation sensor that I wasn't happy with. I'm mis-using it again here (mounted on the bracket above), ignoring the rotation and just looking at the magnitude, which unlike last time gives me a beautiful full-revolution marker (in between which some adaptive dead reckoning is quite sufficient):
I also decided to replace these:
with a DRV8833 breakout board because it's so much smaller and totally silent (and even cheaper than the relays). Here's a quick breadboard test to make sure I knew how to use it:
Soldered it all together on a proper proto board, then fried it while taking last minute measurements (live and installed) with metal calipers, threw it in the trash and then soldered it all together again with plug-in headers this time so I can swap out dead components... (Sigh.)
Here's the end result:
I just stuck an Ikea blackout curtain (cheap, light, and doesn't smell of chemicals) on it with some gaffer's tape and rolled it up. Somehow it rolls up slightly crooked. I suspect it's stretched more on one side than the other since I taped from left to right--I probably should have taped it from the center out instead.
But oh well, it works, and is essentially silent. It takes maybe 10 minutes to open or close, but I have it open in small but exponentially increasing increments in the morning, starting with just a crack, to create a gradual half-hour sunrise like effect.
All told it ended up being more of a three-weekend project than one, alas. (And only that quick because I was drafting the next part while the prior was printing. Though I cost myself a day and much teeth gnashing by frying my board with calipers...)
But I'm already sleeping better, so worth it.
