The last SMD components took a little longer than I had hoped to come in (this past Monday). With that order in, I had all the parts to start populating the Main PCB, constituent parts shown below (SMD resistors omitted).
- Adafruit 1.8" TFT (160 x 128 px)
- Pololu DRV8834 Stepper driver
- 5-way joystick (Sparkfun COM-10063), 6 x 6 x 5mm tact
- Teensy 3.1
- 8-contact FFC connector, 1mm pitch (Wurth)
- Red LED
- MCB73831 LiPo charge IC
- 2P, 4P JST-PH male receptacles
- Assorted 0805 SMD resistors (not shown)
All soldered up, minus the limit switches, which will have to be added later. I'm not a big fan of soldering SMD stuff, even the 0805's. Especially after a cup of coffee in the morning.
Here's all of the electronic bits and pieces. I put a piece of Kapton tape on the image sensor to avoid it getting dirty and scratched for now.
At this point I considered ordering the 3D printed parts - but then I looked at the total cost, and again at my wallet. Nope. Considering my nonexistent budget, I instead went to the university book store, and picked up several planks of basswood ($20) and decided to use parts on hand as much as possible. I had a few 1/8" steel shafts and brass bushings from previous projects, and those worked just fine to make a linear stage. It wobbles a bit, but it will do.
This part I'm pretty proud of! The original plan (for the 3D printed version, which may be a ways off now) was to use a belt and pulleys to drive the linear stage. But those cost $$$ and would take a week or so to come in - so instead I'm using silamide thread (waxed nylon filament used by beaders - it's resilient and pretty slippery, not to mention cheap!) run through the eyes of several sewing needles. Each end is attached to the stepper shaft so that they wind or unwind, making a push-pull sort of arrangement. Tension can be adjusted by the block to the lower left, increasing or decreasing the track of the string.
I'm skipping a few steps here - just a lot of cursing and gluing things together when they weren't supposed to be - but here's the finished first prototype. Yeah, it's pretty chunky, and missing a few of the key functionalities of the final product (namely the ground glass viewing screen). But it works! For now.
The Main PCB is exposed, as I couldn't think of a good way to cover it up and still access the buttons and USB port without routing (something I routinely try to avoid). Works for now, but later I would like to put a piece of clear acrylic over it to protect things.
The next photos show how chunky the darned thing is - about 75 x 120 x 210 mm (without lens). The 3D printed one would have been a lot more svelte, but you get what you pay for, right?
Pop the top (just some black card stock) and you'll see that it's just a basswood skeleton with the electrical bits tacked on inside. A bit of open-cell foam is used to seal out extraneous light and improve contrast.
I left a LOT of room inside to avoid backing myself into a corner. That explains why it's so big and bulky.
The electrical components are just held in by screws or tacked on by some Elmer's glue-all, so they can be easily recycled. The lens is held on by screws and bent-up paper clips, but hey, it works.
Last but not least, there's a small pocket for the LiPo.
Finally - here are some photos straight out of the camera (well, imported to Photoshop as 16-bit PGM, and exported as JPEGs - but absolutely nothing changed in between).
From my apartment window (f/8, 1/500s integration time)
Making dinner (f/2.8, 1/15s integration time)
A rare selfie (f/2.8, 1/60s integration time) - this one has some levels adjustments in PS
Contrast looks way, way better now that there are fewer light leaks, but that is to be expected. I'm happy with the dynamic range and sharpness for now.
Still quite a few things to improve - like the lack of an easy way to focus and compose, and there are quite a few bugs to squash with the firmware.