foone

foone, 20 hours ago

The way this works: You have a blank PCB coated in a thin copper layer, and it's coated in a photoresist material. This material breaks down when exposed to light.

You then shine a bright (usually UV) light at it for a while, and the spots which got hit by light break down, while the other parts (which were in shadow) remain on the board.
You then use a corrosive chemical to etch away the copper layer, but it only etches away the parts that aren't covered in photoresist.

foone, 20 hours ago

So by using these magazine pages as your mask, you can create these PCBs with a chemical developing process and some blank copper-coated PCBs.

That's really cool!

foone, 20 hours ago

Normally you'd do this by printing or photocopying onto transparent paper, but I think they're saying you can just turn up your brightness/wait longer and blast the light straight through the paper.

I wonder how well that worked?

foone, 20 hours ago

And of course on one of the following pages, they had ads from companies who were happy to sell you the chemicals and equipment needed to make circuits this way.

foone, 20 hours ago

The cool thing about this kind of photoresist PCB etching that may seem surprising if you know how circuit boards are designed today... you could totally do this without a computer.

Fundamentally you just need to come up with a photomask: that's some dark black ink on a transparency. You could use stencils and stickers and markers to make that, then turn it into a PCB. The only electronics you need is a bright light.

foone, 20 hours ago

it's just neat to think that today PCB design is "you use this complicated program on a computer then send some files to a place that mails you back a bunch of PCBs", when 30 years ago it would be more "you carefully do some arts & crafts with stickers and then some chemical processes"

foone, 20 hours ago

It's similar to how "amateur photography" went from "you have a dark room and a bunch of chemicals" to "you have a phone in your pocket"

foone, 20 hours ago

@jordan I think that's a futurama joke.

but yeah, I love the idea

foone, 20 hours ago

@drewfitz yeah, this design here is a two-layer one!
I'm not sure how you do that. I guess you just expose it twice, once on each side, and then do the etch step once?

foone, 20 hours ago

@darkling yeah the vias are real tiny, so you need a fast drill with a very tiny bit, so it's a little tricky to do by hand.

foone, 20 hours ago

@Jencen certainly. Especially if you scan them, clean them up a bit, and print them out onto transparent sheets

foone, 19 hours ago

@cadey you have big pockets

foone, 18 hours ago

@kurth @f4grx @gsuberland these look tasty. some kind of fried chicken!

foone, 21 hours ago

@Ezhik @hikari but frankly many of them should have been

foone, 20 hours ago

My proof of concept print is done.

foone, 20 hours ago

So it gets photographed at this angle, rotates to this, then to this, and then to opening-down to drop the flop.
Rinse, lather, repeat.

image/jpeg
image/jpeg

foone, 20 hours ago

@Thorsted Yeah, but by this point I've already imaged the disk, so I know what format it is

foone, 20 hours ago

@mctwist I intend to release my designs once this is more finished, yeah.

The big problem is that it depends on an existing floppy copier which you need to retrofit: so it's not a from-scratch solution. I don't know if I'm going to get to a design I can build from scratch, but it'd be nice

foone, 19 hours ago

Next step: Widen up the slide area a bit so it's smoother (ideally I'd have metal or something here, but maybe I can sand down the 3D printed surface), add holes for rods to hold it at the right width, a mount for a bearing on one side, and a servo motor on the other side.

foone, 19 hours ago

but the purpose of this print was just to hold it in my hands and confirm I wasn't completely off base with this idea

foone, 19 hours ago

The servo motor might not be the best way to go, it might be better to use a geared system with a stepper motor, but that's more complicated. So I'm probably going to build it with a servo motor and only look at the stepper motor option if that doesn't work out

foone, 17 hours ago

@f4grx I think that's mostly what I'm doing, I think? I just designed it as circles to make it easier to support and test.

Aside from the moving the camera to avoid focus. I might end up doing that if it's simpler than adjusting focus.

foone, 12 hours ago

@marcel I've thought about that! The issue is illumination + moving it steadily.
But it's definitely something to look at