Let’s make a solar tracker! or — how to use a couple extra stepper motors.

I have 3 more stepper motors left over from the star tracker project and I have an idea.

One thing I realize is that mid summer is not really such a good time to be doing astrophotography, since there are so few hours of actual darkness. So how about some solar observations?

I tried was hold a rod on my driveway and measure the compass direction of the shadow, and wow it was within 5 degrees of where it should be (comparing to a solar calculator app). But wait! Why is it so far off? Is the sun in the wrong spot?

I don’t know, so I’m going to get a little more technical and try to track and log sun positions.

There are several examples of solar trackers online, things that use photo cells or photo resistors and either simple motors or Arduino setups that point themselves towards the sun… What I’d like to do is to do that, but also do data logging of where the sun is.

So a simple design would be an alt/az tracker, I bought a bunch of photo resistors, I have a 3d printer and I have spare microcontrollers, and I even have a GY-511 accelerometer/magnetometer module so I should be able to sense the direction and angle of inclination of the tracker. I need to order an SD card module oh and a 3.3v regulator — don’t depend on the microcontroller’s on board regulator for the SD card reader — it actually draws quite a bit of milliamps.

So that’s the plan and of course I will keep progress posted here and on Youtube.

Update: Because I’d rather not wait for an SD card reader to come in, as long as the ESP 32 can run a web server, I’ll just have the ESP 32 and the GY-511 onboard, I’ll do the data logging in the house with one of my Raspberry PIs. Nice thing about this is I also don’t need the external voltage regulator because the GY-511 takes 5 volts in, I can grab that from the USB power pin. So I’m going to need 8 data pins to drive the steppers, and 2 pins for i2c to communicate with the GY-511, and it looks like that will just work out… the ESP32 I’m using is the MH-ET LIVE MiniKit. It’s a compact design, so instead of a long board with a row of pins on each side, it’s half sized, so two rows of pins right together on each side. To use it on a bread board you’re limited to just using one row on each side, so though the board has lots of GPIO, on a bread board you don’t have access to all of them (Unless, as I’ve done in the past you use a row on each side for pins that plug into the breadboard, and then pins facing up on the top for the other 2 rows..