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twistedsymphony's adventures in making PCBs.

twistedsymphony

twistedsymphony

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I've started dipping my feet into the pool of designing my own PCBs, and wanted to put together a work thread to share what I'm up to.

A few months back I made a few small PCBs for some experimentation, and more recently I did my largest PCB yet in the form of a simple multi for the Metro VG420 hardware.

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twistedsymphony

Thread 'Metro VG420 Multi interest and development thread?'

I'm nearing completion of a Multi-board for the Metro VG420 hardware.

Why this hardware? Why make this multi?
Well I really wanted Sky Alert and Karate Tournament, both very expensive PCBs, and I wanted to figure out how to convert a cheap Toride PCB to either of these games. I managed to do it but it required some additional circuitry to do so and that additional circuitry was most of the way to a multi, all I needed was some bigger ROMs and a way to bank switch them. So I decided that since the hard work was already done I might as well take it the rest of the way and make a full...
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followed by my smallest PCB ever in the form of a rotary selector for the CPS3 Ultra SIMMS
img_20250409_172438742-jpg.187573

twistedsymphony

Post in thread 'Replacing UltraSIMMs DIP Switches'

that didn't take long :D
ds_cps3_rotary_selector_pcb.png
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If anyone else is interested in getting into this: I'm using KiCAD and here are some of the video guides I used to get me started:
View: https://www.youtube.com/watch?v=sEGyNfBuPig

View: https://www.youtube.com/watch?v=qw9WIm5M5R4

View: https://www.youtube.com/watch?v=pV-4ElYoXYU


That last video was probably what helped me the most as a lot of the standard parts needed for the stuff I wanted to build were too old or uncommon (or both) to be included in a lot of the databases. So a big hurdle was putting together good symbols, footprints, and 3D Models for the parts I wanted to use

so yeah, I hope to share some nuggets here about what I'm working on and happy to knowledge share with others who want to start making their own PCBs as well.
 
the PCB I'm working on now is another multi... and NOT for the VG460 hardware :D

8makusat.jpg


In this one I'm incorporating all of the lessons learned from the VG420 and doing things a bit more professional and repeatable and designing with manufacturability in mind.
 
Impressive. Definitely looking forward to what your next multi is along with playing a ton of vg420 very soon.
 
Very cool. I appreciate you sharing how you got started. I've always wanted to get into PCB design but figuring out where to start can feel overwhelming!
 
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I really love the simple bank-switch multis as opposed to the really complex multis with on-screen displays or other complicated stuff.

because the bank switchers are really no different than an easy way to do a ROM swap so it helps ensure that the games are running as close to original as possible. and the instant game switch without any loading is nice too.

The Rotary Switch is something I really like instead of dip switches on these simple multi kits, a simple 8 or 16 position knob is much more user friendly and nice looking than a bank of dip-switches.

PT65501.JPG


It's been difficult to find these at a reasonable price though.

the Apem PT65 series is the one I'm using so far:
https://www.apem.com/media/apemProduct/PCB_serie_PT65_10_11_2021.pdf

It's a nice little switch but the price is damn near $15 which is robbery for what should be a <$2 part.

The only other models I've found with a nice "segment wheel"

the only other options I've found are:
1. Gray Hill 94 series:
https://app-grayhill-website-cms-prod-001.azurewebsites.net/media/xvhksa34/94h-datasheet.pdf
they sell the knob separate from the switch and once you buy both it's not much cheaper than the PT65, not to mention it's a much uglier looking switch.

2. E-Switch RDT series:
https://configured-product-images.s3.amazonaws.com/Datasheets/RDT.pdf
These actually have a reasonable price, but I can't find any evidence that the version with a segmentation wheel actually exists anywhere for sale.

searching around Alibaba the only evidence of any of these is this one listing which shows a picture of one of these switches:
https://www.alibaba.com/product-det...offerlist.normal_offer.d_title.410813a0njNhYq

there's no clarity on the listing on how to spec that version of the switch though, I've reached out to them for more info but haven't heard anything back in over a week now, so I have little confidence that anything will come from it.

Anyone else know of any other options here? it's be really great to find a <$2 option
 
Ape Cosplay said:
I have to ask, is your logo a glider from Conway's game of life?
Click to expand...
yes it is!

20+ years ago, in college, I learned about Conway's game of life and the Linux hackers who had adopted the glider logo to represent themselves:
http://www.catb.org/hacker-emblem/

I liked this idea and what it represented but wanted to make a variation on this to represent me and the hardware hacking I loved so I took the glider formation but represented it as squares instead of circles (hard edges for hardware rather than soft edges for software). I've used this logo in many places since. I've used it as an avatar on the web over the last 20+ years (though not here on AP), It was part of the bit-district logo when I was selling 3D prints and I even have a 3D version that I drew and had tattooed on my shoulder many years back.

AlxUnderBase said:
can be inserted solid-orange there / bit-district by @twistedsymphony . how sounds ?
Click to expand...
I considered it but would rather not. I'm happy with just the logo
 
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So here are some tips that has really helped me out, especially with these big PCBs that need precise pin alignment in sockets.

Of course using the grid feature in the PCB editor is the first step. pinspacing on normal DIP chips is 2.54mm (or "100mills") so make sure you grid is setup to a derivative of that. I've found that going at half hat size (1.27mm aka 50mills) will ensure that all of the chips will be snapped to the right measurement. Then you use calipers to measure distances between chips helps a lot.

but I had an EE that I work with recommend I print out my PCB layout to test fit before sending the PCB to fab... this has been a game changer!
IMG_20250208_220331886_HDR.jpg


this allowed met to quickly double check that all of the chips are in the right spot and the right size, and also gave me really great visibility as to what is under the chips so I can make sure I have good clearances between pin legs and any taller components like socketed chips on the lower board.

Another UPGRADE to this technique has taken this even further. Assuming you're working with a nice PCB that has straight pins on the solder side, you can place you paper model UNDER the PCB line up some pins for chips on opposite ends of the paper and puncture the paper with the pins. then continue through puncturing all of the pins for every socket header you've got on the sub-board you're designing. Then you can peal off the paper and the puncture holes should all line up with the chip pins on your print out... if they don't you should have a clear indication of how far off they are and in what direction.

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for the VG420 PCB I probably printed and re-printed the paper a dozen times to dial in the pin spacing. figuring out the pin puncture concept for the VG460 and this new ***** multi I was able to dial in the chip spacing in just 2 or 3 prints. And of course the best part is really high confidence that the pin alignment is going to be right when you send the PCB to fabrication and blow a few hundred bucks and a few weeks of time to get the boards made.
 
Since a lot of the dip based multi kits have had custom OLED selectors made for them I decided to keep this in mind when making my multis. Though I decided to get this worked out before I sent my next one to fab just in case there are any changes I need to make on the multi side.

I found this really nice Adafruit ESP32 based board with 3 buttons and a full color TFT and just started playing around with it today.
IMG_20250426_174835158_HDR.jpg

This picture doesn't do it justice the image quality is surprisingly great for what it is.

My hope is that I can have one selector design that will work with any of my multis and just needs a config file changed and new images added.

The nice thing about ESP32 is it also enables a wifi interface as well!
and with a full-color TFT it means you can just drop a PNG on it for the game logo instead of having to make custom pixel art like you with the OLED displays.
it has 4MB of storage too so there isn't even an SD Card, you can just plug in USB and drag and drop files onto it.
 
I've spent a good chunk of the weekend relearning python and programming this thing. I'd say that the software is 99.9% complete for serving as a game selector:
View: https://www.youtube.com/watch?v=HlgGEeJghjA


my shitty cellphone camera makes it look washed out but the display is really quite vibrant in person.
I spent a lot of time to get it responsive, it limits the images to 8-bit BMPs but it swaps images the instant you push the button instead of taking 1.x seconds to process a jpg or png. If images aren't present it display a text name of the game and scales the game title to the screen size so you don't end up with truncated text or text so small you need a magnifying glass to see it.

I've designed it to be completely user customizable too, so you can change the game name text, font color and position on the screen, image files, customize the game rotation order, set a default game to autoload when you power it on, or have it re-load the last game you were playing. you could even have the same game appear multiple times in the list if you wanted. Pretty much anything that could be changed without breaking it was put into the config file. that way no one has to muck with the code at all.

I also have a separate config file for the parameters specific to the multi you have it attached to, for things like number of dips, if the dips are high or low when on, and how long to hold the mobo in reset while swapping games. This way you don't have to worry about mucking up the critical functions of the multi board interaction when you made changes to how you want the games to appear on the menu.

I do need to design a small PCB to interface this board to the multi board. As for functionality I haven't jumped into setting up a web-server yet but it's on the to-do list.
 
And here is it actually functioning on the multi!
View: https://www.youtube.com/watch?v=rPfUV6X7EA4


as you can see it could use a small adapter PCB to make the connections nicer, I also plan to add some protection circuitry there to help with voltage protection. the ESP32 is not 5V tolerant, but the design of the multi is such that as long as I leave all of the dips to 0 on the multi board the ESP32 is doing all of the driving. Honestly surprised I can bank switch EPROMs with only 3.3v outputs.
 
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