All New Coleco Adam Internal PSU
Added 2019-11-14 15:20:37 +0000 UTCEDIT: Final version here https://youtu.be/i4nYqfZlnMY
Here's an early preview upload of the Coleco Adam Internal PSU! I accidentally uploaded this to my test account because I used a python uploader I've been working on and forgot to change out the oauth token file.(Here's that project if you're curious: https://github.com/AkBKukU/youtube-cli/ )
There was about 12hrs of footage for this video, 9hrs of that was screen capture of creating the schematic and board layout. I originally cut it down to about 1.5hrs run-time, but it was painfully slow pacing. I decided to try and cut it down a lot more. I got it down to half that but I want to trim it down a bit more still
I need to re-record the part where I talk about uploading PCBs to make it shorter. This video is sponsored by PCBway but I also wanted to talk about the PCB ordering process a bit. I think I rambled on a bit too much for that part and it will seem a bit too shill like. I was really just interested in some of the features available.
I also need to come back for one final pass on the second half of the video because the pacing really drops to a crawl. Also, I updated my camera in the middle of this (they added a an accelerator horizon feature!) and I accidentally changed the color setting for the footage that was saved I baked in an extended video LUT). It was much more difficult to color correct those shots..
I'm very happy with how this project has turned out! I'm really looking forward to these being available for people to put in their systems. Here is the repo for the project: https://github.com/AkBKukU/adam-psu
Comments
My vacuum tool build was likely around $30 total, and most of that for the pump. The miscellaneous parts can be sourced from a broken Kruigs, and those are pretty easy to find. The mosfet driver board I used was a left over PCB from an LED project. https://i.imgur.com/8pubuLG.jpg https://i.imgur.com/9wJG6Yy.jpg https://www.sparkfun.com/products/10398 I'm currently working on a proper PCB for it. Going to be ordering PCBs anyway, so adding a few more of another design is almost free compared to the DHL shipping costs I'm already going to pay. I could make it a kit, but not sure if there would be any demand for such a thing. The DIY reflow oven is the cheapest route, even the kit I used was a lot cheaper than the small import units. $800+ is a bit hard to justify on a single time saver tool for a hobby.
Kadah
2019-11-17 12:56:30 +0000 UTCI don't have a hot air station, it's one of many EE tools that are on my list of things to get along with a programmable load, digital oscilloscope, sig-gen, better DC PSU, etc. So far I've been able to get by without it but if I'm going to be producing these regularly then I'm probably going to want one. I've used one in the past at work and they are great. Especially for rework. I was thinking more about going the reflow oven route since these boards are easily small enough to fit multiple in even a small one. I may build/buy a vacuum tool at some point, but I'm pretty good with tweezers so it's an expense I can put off in favor of other things that will have a larger impact. Oh the stencils are definitely going to be worth the investment to me when I finally get setup for reflow. The design likely wont change for a long time and it will quickly pay for itself in time. I did some quick tests of 1x1 vs 2x2 on PCBWay for ordering a panel and it didn't scale well. I would say this is a medium sized board though. That is something I could shop around more for later. I did some other testing and it looked like my assembled board cost would be $3.30/board up do the 200qty point where it started to drop down to $2.61/board. But there's no way I'll ever be ordering more than 10qty assembled boards, if I go that route, because the BOM cost(without PCBs) for these is about $10-12 right now. So it's a significant investment to have sitting around. PCBWay has a "provide your own parts" option that is much more expensive in low volume but at 200qty only added $0.40/board. And you can mix parts who provides parts for no added cost. I assume they want to provide passives for that. For v0.2 I'll still be ordering unassembled so I can test the high side switch. For v0.3 I'm going to play around with some lower cost buck regulators and caps to see how far I can drive the price down, so I'll want too hand assemble again. Once I've lock down a v1.0 I'll probably try an assembled order.
Tech Tangents
2019-11-16 16:02:21 +0000 UTCHand soldering SMD... Got a half decent hot air station? Get some SMD291AX solder paste. It will last over a year refrigerated, just let it warm to room temp for at least half an hour before use. I run my crappy hot air station at around 150C to warm the board up for a minute or three (do this on a silicone mat!), then bump it up to 230C to reflow. Reflow is very forgiving and it takes less paste than you think. I ended up building a reflow oven last year. This was completely worth it even though I only use it a few times a year and its always in the way. Went with the Controleo3 kit and a TO1313SBD oven off Amazon. Its not cheap, but I priced out most of the necessary parts and the kit price was on par when including shipping and my time sourcing everything. For placing components, I made a vacuum pickup tool using the SparkFun 12V vacuum pump, 2 pneumatic solenoids (salvaged from a broken Kurig, used to make and release the vacuum), a 3 pedal dictation foot (the extra switches used to change the pump speed), an Arduino clone, and some aquarium air tubing. I did try a valve reversed aquarium air pump, but it did not create enough vacuum pressure. The tool handle itself could be made from a hallowed ink pen tube and a bent solder paste needle. Solder paste stencils, even for a small batch, to me its worth the $7 and some wasted paste not having to hand paste every pad on a panel with a 100+ pads or doing more than one panel. Panels of small board are often the same price, or barely more expensive, than a single. I have a small board I'm working on now, 1x9CM, I can get 5 for $5 or 200 in panels of 40 for $16. PCBWays assembly service seems cheap at first because the 10 board cost is a special price for simple designs and is cheaper per board than at 200 qty for the same board. I checked one of my small designs (24 SMD different parts, 60 total) and for 10 it was $373, not including the cost of the parts. The price gets down to $10/board at 200 qty. JLCPCB's SMD service might be cheaper depending on the design. Their components are limited to what they have listed for the service (which is fewer than offered through LCSC), and any non-basic "extended" part have a $3 fee per part number per order. If you use all basic parts, it looks like they could be the cheapest option I have seen for runs less than a few hundred boards.
Kadah
2019-11-15 10:29:11 +0000 UTC
