Putting Things Together

phototransistors wired with shift registers

This is a quick update on the Throw project. It’s still moving along. The photo-transistors (sensors) are wired and working, and I’m able to read all 72 of them in under the millisecond that I needed! Here’s the wiring setup for that. Of course they won’t be plugged directly into the breadboard like this in the final product:

phototransistors in breadboard

I decided that I’ll be using 80/20 extruded aluminum frames to hold all the lasers and sensors, and I’ll attach these to a wooden backboard, with rubber bumpers between them to deaden vibrations between the electronic equipment and the wooden backboard/housing. Then around the 80/20 frame will be a removable wooden cover plates to allow for access for maintenance. The plates on the inside will have holes to allow for the laser beams to pass through. Here’s a rough section of what it looks like.

section cut of 80/20 mounted to wood backboard

I started to assemble the frame, and mounted some of the lasers to test the accuracy. I started off by ordering some of the caps that fit into the 80/20 slots, and drilling holes in that to mount the lasers. My thought was that I’d mount 8 lasers, and then power them up and see how accurately the beams were aligned from 4 feet away, to see if they’ll even hit the sensors across from them.

And here’s 8 diodes mounted in the 80/20:

8 lasers mounted for test

Unfortunately, the lasers were not accurate enough mounted in this manner. It looks like I’m going to have to calibrate each diode as I mount them. So I think the next step will be to mount all the sensors using a plastic track like this. Then assemble the 8020 frame completely, and calibrate each laser until it’s hitting the proper sensor, and hot-glue the laser diode in place. It’s going to be a lot of work, but it’s coming along!