How to make INSANE Resin 3d Printing Timelapses

For this project, I wanted to find a way to capture super smooth resin 3d printing time-lapses, but since resin printers (at least mine) doesn't support USB communication and OctoPrint doesn't support resin printers, my usual method of making time-lapses is off the table. 

Instead, I initially used a light sensor module, a Raspberry Pi and a USB cord to tell my camera to trigger the same way I do with OctoLapse. This method worked great, but I didn't like how much time it took to setup and how long the Pi took to boot up each time I wanted to use it. Furthermore, the Pi required an external power source and a USB connection to the camera, which was too many wires for my taste.

So I went back to the drawing board. This time, I wanted to speed up the initial setup as well as the boot time, so I switched to an Arduino Nano. Instead of using a USB cable to trigger the camera, I switched to a 3.5mm jack and utilized the 2.5mm remote shutter input on the side of my camera. Now, I had a simple solution that booted up quickly, but before I plugged it into my camera, there was one more thing I needed to add. I personally didn't feel comfortable plugging externally powered electronics into my camera, especially if I had made those electronics. So, before testing it out, I added an opto-isolator between the Arduino and the 3.5mm jack. This way, the Arduino tells the opto-isolator to turn on it's internal LED, which in turn allows the camera's own 3.3v signal to travel through the photoresistor on the other side of the opto-isolator. This way, the camera's electronics are completely isolated from the potentially janky electrical work I did.

But... I still wasn't happy with this solution.

The Arduino still required initial programming, albeit not very complex programming, and it also required an external power supply. So, instead, I took a closer look at what the opto-isolator was actually doing, and the final solution made itself clear to me. The opto-isolator functioned by using an internal LED to shine on an internal photoresistor. When the photoresistor has light shined on it, it lowers its resistance allowing voltage to flow through it. With that in mind, I simply externalized this setup, by grabbing a photoresistor and a small 10k resistor, and connecting them to a 3.5mm jack. Now, I am again using the camera's own 3.3v signal to drive this electrical circuit, so worst case scenario, the camera will think I am holding the shutter button down with my finger. I also have managed to get rid of all the external power requirements, and the only cable I need is a 3.5mm to 2.5mm adapter cable. All that was left now, was to solder it up and attach it to my printer!

And there you have it! I'm not able to quickly and easily capture silky smooth time-lapses of my resin 3d prints, with nothing more than a remote shutter cable for my camera. My circuit detects the UV light flash from each layer of the print and triggers the camera once per flash. Make sure to check out my video on this project if you want to see those time-lapses and don't forget to subscribe to my channel!