Horizontal plantation blind automation

I couldn’t find a product that was reasonably priced that looked like it could even handle automating the blinds in my house. They’re horizontal wood blinds that use two strings to adjust their angle: pull one and it goes one way and vice versa.

I started off the day working on some 3d models to adapt a RC servo to the square rod that controls the tilt of the blinds:

After the quick and dirty model printed I tested it out and it seems to work well enough.

Next I modeled something to hold the servo still while it’s mounted to the rod

I’m planning on having a NodeMCU connected to a group of servos so I can control it via MQTT. I was planning on adding a sun load sensor as well as an internal temperature sensor(in the sunlight) to do automations:
Open the blinds if the sun is up and the temperature in the window isn’t significantly higher than the temperature in the room, etc

Any thoughts on the project thus far?

I don’t have any suggestions at the moment, but I do have the same type of blinds so I would like to know how things work out. I hadn’t thought about automating them.

Got the parts all printed up and pulled down a set of the blinds I’m actually intending to automate and the hardware’s different. Back to the drawing board.

The mechanism that turns the rod inside of the blinds can’t be back-driven by the servo so I had to remove it. This leaves no way to adjust the blinds without having the automation system involved. I designed a little pull chain type system that’ll slide in the blinds in place of the existing cord


It uses standard roller microswitches and will be actuated by a single string that will have one of the original pull beads. The controlling nodeMCU module will read this input and adjust the blinds in a sweep pattern until the user releases the pull string.

I burned out my arduino when something disconnected from my rigged up testing breadboard and shorted so I’m awaiting new ICs from the big rock candy mountain. I ordered a bunch of microswitches, servos, springs (not sure if I’ll need 'em), servo cable and crimp connectors, and some nodeMCUs so they’ll be here in 2-3 weeks.

I’m not sure how to adjust the automations when someone uses the pull string to change the angle of the blinds. Any suggestions there?

I was planning on doing a thermal sensor or photocell to close the blinds at least partially based on the intensity of the sun but I’m unsure what to use. Can’t use anything IR based since the glass will filter that. Should I just use a set of temp sensors, one in room out of the path of the sun, one on the other side of the blinds and take the differential?

Here’s a picture of the wrong size stuff

Image of the pull chain prototype

Used a cherry switch I had sitting around until the roller switches get here to make sure everything will fit and work.

I found some small gear motors that may work if I put two in to actually handle lifting the blinds so I’m printing one I drew from the tech drawings to see if they’ll fit.

The motors will just barely fit. I’ve ordered 2 motors, a dual channel H bridge, a 12V-5V step down and a WeMosD1 to test the stuff. It’s on the slow boat from China so it’ll be a while. In the mean time I’m working on designing a switch that’ll handle local control of up/down. Externally it’ll look just like it does now except there will be one cord with an Up arrow on it and one with a Down arrow.

Anyone have any thoughts as to limit/position control?

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