Analog Discovery Plug-In Module

Background

I recently picked up two Tektronics TM503 "mainframes", along with multiple plug-in modules. I bought one for a great price at an electronics store in Tucson, AZ, and then ordered the other one off of Ebay. My goal was to create a budget testbench for my electronics and ham radio projects. One of the modules is an oscilloscope, which I planned to use often. However, I later realized that the CRT display was messed up and after debugging a bit, decided to push off fixing it as it wasn't worth the time or risks. However, I love the look-and-feel of the TM503 mainframe with instrument slots, so I decided to find a way to integrate my Digilent Analog Discovery 2 (which has two scope channels, wavegenerators, and GPIO) into the TM503 system.

Design

I designed a custom PCB that attaches on to the empty "toolbox" module I got with my TM503. My goal was to attach this to the faceplate of the module, and place the DAD inside the box. This worked way better than I expected, and the finished PCB design and images can be found below. I used Altium for schematic capture and PCB design.

The PCB splits out the DAD's scope channels, waveform generators, and trigger pins. These signals go to BNC connectors. I also added switches to change waveform output impedance between 0 ohm and 50 ohm, as well as a bypass cap on switches for the scopes to select AC-coupling. These additions were based around the Digilent BNC breakout board that they make for the DAD.

I made sure to add a front-facing connector on the PCB that allows me to use a ribbon cable or dupont jumpers instead of BNCs. This also allows me to use the GPIO pins and power supplies on the DAD, from the PCB.

Connection Problems

After receiving the PCB from JLCPCB, along with the necessary components and connectors, I realized that the pinout of the DAD pass-through connector would require a different ribbon cable. I reluctantly ordered one from Digikey and mourned the paused state of the project.

Final Results

After getting the new ribbon cable hooked up, I tested out the system and was pleseantly surprised that it worked amazingly! I have used the module multiple times since building it, and look forward to having it be a staple on my workbench. My only gripe so far is that when I want to use the DAD on my computer desk, I have to take the DAD out of the module, since it takes up too much space inside the TM503 to be on my other desk.