Electronics > Projects, Designs, and Technical Stuff
DIY Modular Test Equipment Project
<< < (9/29) > >>
void_error:
Realized the digital output driving solution is dumb just because I can get away with using MOSFETs. Oh, and I'm at the 500 pin limit of my DipTrace Lite license, that's another reason using 74AHC125s is dumb, and yes, I was too lazy to come up with something else. I guess I just can't get away from DipTrace because I've been using it for a long time and I didn't need any tutorials to figure it out. Eagle would be another option, but the free version has a 80x100mm board limit, useless. KiCAD is a pain in the ass to use, installed it for the third time and then uninstalled it after 10 minutes, Circuit Maker has the annoying thing of having to be always online... anyway, rant over.

Mounting holes might cause me some problems, mainly because everything has to be stackable. The UI board is quite crowded, as you can see in one of the previous posts, but the 80(H)x100(W)mm size is pretty much what I'd like to stick with, or if it's not possible, something with nice round numbers. The main problem with the size comes from the fact that the Waveform Generator board has to be at least 70mm wide because of the locations of the mounting holes on the UI board and has to extend about 20mm below it because of the BNC connectors. So far it's 100(H)x80(W)mm.

On top of that there are going to be 2 Aux Power Supply boards, one with the Analog supply rails, the other one with the Digital supply rails. They'll have to be supported mechanically by the Waveform Generator board, that means 4 extra holes. No room for 4 mounting holes on the UI board but I won't need them there anyway.

Another plug-in board would be the digital isolation module for the Lab Power Supply, that will require only +5V which will be provided by the same board that powers the digital part of the Waveform Generator. I'll have to keep that in mind then I design the Aux Power Supply modules.

An alternative to the boards directly plugging into each other is to use angled pin headers and a pieces of stripboard (soldered or with connectrors) linking them together. Not very elegant but it would do the job. In any case spacers will still be required to keep everything from falling apart.

Finally, I've decided to make this Open Source, and I'll probably do some (rather amateur-ish) YouTube videos if I have enough time after I assemble and test the first boards. GitHub stuff coming after that. Stay tuned for more.

Oh, one more thing, does anyone know any free 3D modelling program that accepts .step or .wrl models and it's to use so I can check if everything fits together perfectly?
altaic:

--- Quote from: void_error on June 16, 2016, 07:00:44 pm ---Finally, I've decided to make this Open Source, and I'll probably do some (rather amateur-ish) YouTube videos if I have enough time after I assemble and test the first boards. GitHub stuff coming after that. Stay tuned for more.

Oh, one more thing, does anyone know any free 3D modelling program that accepts .step or .wrl models and it's to use so I can check if everything fits together perfectly?

--- End quote ---

Very cool, thanks!

On the open source CAD front, I've used FreeCAD and BRL-CAD, both of which have matured quite a bit in the last few years. The easiest option in this case, though, is probably Autodesk Fusion 360, which is "free for students, enthusiasts, hobbyists, and startups."
void_error:
FreeCAD seems to do the job, if I export a .wrl model of the board. Easy enough to use for basic stuff like adding boards on top of each other which is all I need to do.

With that said, having the BNC connectors of the Waveform Generator sticking out right below the UI board seems to be a bad idea so I'll move them to the left side. That implies rotating the Waveform Generator board 90 degrees and relocating a few connectors.

The result will look like this: (from left to right) BNC connectors -> Display -> Encoders. Buttons right under the display as seen in one of the previous posts.

I'll start working on it after my badly needed 12 hours of sleep...
void_error:
Had a few 3D models for the pin header corresponding sockets used to interconnect the boards and started looking around. TE Connectivity seemed to have all the 3D models I needed.

Unfortunately their servers give me this after a few attempts. :wtf:
"(error 21) [ERR_NO_RESOURCE_AVAILABLE] CoreApi(allocate) A predetermined resource limit has been exceeded. Further connection attempts will be refused until sufficient resources are available. Your patience is appreciated. Please try again later."
:palm:
void_error:
Found the 3D models elsewhere but had to register to be able to download.
Anyway, problem solved which means I can post a nice 3D preview of two of the nearly completed boards, the UI and the Waveform Generator.











Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod