well, I will probably use oshpark to make a classic REX pcb, and see how well it goes. I already have the "large diameter pin holes" which yes this board could use. I could post the diameter I use. It is a lot faster to just trim the panelization tabs than to grind the whole thing.
On Thu, May 26, 2016 at 1:11 PM, Brian White <[email protected]> wrote: > The cad files are right up there on oshpark. > > I did have to sand down the edges a little because the "rat bites" landed > right in the middle of the edges, which screws up 2 half-holes on each side. > You can see it on 2 of the pictures of the bare new boards before sanding. > Just zoom in. > > As for spacer, yes, also shown in the pictures. You definitely need a spacer > bock to prevent the board from going too far into the socket, beyond the > "peaks" of the socket pins. I found some thick paperboard stock at the hobby > shop where I got the extraction ribbon from, but you can also just use 3 or > 4 layers of cereal box. I just hot-glued the ribbon and card stock. > > I clipped the backs of the jumper pins close to the board and used the hot > glue to level up the ribbon and card stock so the spacer ends up parallel > with the board. > > The ribbon is just common 3/8" ribbon from a craft or fabric store. Michaels > in my case. > > I am not the designer just to be clear. He just whipped this up after I said > I wished it existed, supplied the pinout reference, and then I made several > suggestions which he did, and then I ordered a set from oshpark and finally > now have tested it. > > I think he's going to make at least one more small change, which is just to > make the half-holes slightly larger so the socket pins drop in better. But > obviously it's already working as it is. > > I think some silkscreen indication to show which way the module goes in the > socket would be good. There's no good way to key the pcb like how the > original molex carrier is keyed, unless you poke holes in the ribbon which > would not be ideal. > > -- > bkw > > On May 26, 2016 11:17 AM, "Mike Stein" <[email protected]> wrote: >> >> As a matter of fact I was thinking about making a RAM ExtRam clone (poor >> man's REX ;-) and was wondering the same thing, how to avoid having to >> shear/grind the edges. >> >> How'd he do that? >> >> m >> >> ----- Original Message ----- >> From: "Stephen Adolph" <[email protected]> >> To: "Model 100 Discussion" <[email protected]> >> Sent: Thursday, May 26, 2016 6:43 AM >> Subject: Re: [M100] New option rom module >> >> >> > well that's very interesting; I had assumed that since my layout tool >> > would fail the design if I put the board edge down the middle of the >> > vias, that no one would build with that error. So, I hand grind REX. >> > >> > >> > On Thu, May 26, 2016 at 6:40 AM, Stephen Adolph <[email protected]> >> > wrote: >> >> hey, cool. didnt you get a board violation for putting the board >> >> perimeter in the middle of the via? >> >> do you need a spacer under the board when in the socket? >> >> >> >> On Thu, May 26, 2016 at 1:04 AM, Brian White <[email protected]> >> >> wrote: >> >>> Just verified a new option rom module design. >> >>> >> >>> Adapts a 28C256 SOIC to a Model 100/102/200 option rom socket. >> >>> >> >>> Allows re-programming the eeprom after the chip has been soldered to >> >>> the >> >>> module. A pullup resistor and a jumper on-board allows >> >>> enabling/disabling WE >> >>> on the eeprom as needed. >> >>> >> >>> There is a special programming adapter to make it convenient to >> >>> re-program >> >>> after soldering the chip, but there's a problem with that, so at the >> >>> moment >> >>> you can still program (re-program) using a dip28 test clip and >> >>> manually >> >>> arranging 28 jumper wires. Not the most convenient but functional. >> >>> >> >>> This is essentially the same as "ROMBO" or "MOMBO", but now it's an >> >>> open >> >>> source design up on oshpark and anyone can get one whenever they want. >> >>> >> >>> Home/self assembly isn't too bad. You don't need anything but the >> >>> parts and >> >>> a plain soldering pencil and some flux and solder. The soic chip was >> >>> simple >> >>> using the "drag technique". It's simple, just search "solder drag >> >>> technique" >> >>> on youtube. The trick is just the extra flux pooled around for surface >> >>> tension. >> >>> >> >>> https://oshpark.com/shared_projects/4dLqXOs0 >> >>> >> >>> https://goo.gl/photos/Zs8ZnmDco9BwgDDBA >> >>> >> >>> -- >> >>> bkw
