Suggestions wanted

I am finally building something that I have wanted to do for a long time now: a portable breadboard development station.

I have been piecing it together with stuff I have accumulated for the project over a few years (just never got around to completing it.) What it is right now:

It started life as a slim clipboard with storage for about $7. I disassembled and installed a portable DVD battery that I had picked up on clearance years ago for about $10. The battery outputs 12V and has a smart charger with it. I installed this and the jack using heavy duty double sided 3M tape. Cut out a slot in the side of the clipboard bottom to install the jack.

I also bought a tiny 3A switching power supply that was designed for an LCD. It has 12V (actually just straight from the jack) 5V and 3.3v supplies. All rated for 3A each. I built a little adjustable supply from a LD1084V and connected this to the 12V out. This would give me a voltage from about 1.3V to 10.7V. The purpose of that is for powering motors and other items. However, I found in my junk bin one of those vehicle selectable supplies that had burned up. The ones with a switch to select between fixed voltages. The 120 ohm current shunt resistor burnt up. It had an LM317 adjustable regulator installed. It is also lacking capacitors on the input and output. So, I plan to install a LD1084V regulator in there, beef up the resistors and install some quality low ESR capacitors (10uF on input and 470uF on output.) I may even go a little nuts and install two 470uF caps on the output for extra stability.

There will be a switch and LED installed to turn the whole thing on and off and be able to tell when it is on. The plan is to also wire the voltages up directly to a power bus on the top so I can just tap into the supplies I need. I have not decided exactly how I want to do that. My options are using quick-connect terminals (like screw terminals but with levers for installing the wires) or I could just wire directly to a set of breadboard power rails.

Aside from the power supply inside, I plan to install partitioned parts storage for some common items that I use like jumper wires and “staple” jumpers.

On the top side, I will be installing a series of breadboards arranged around a custom arduino board (I plan to use a 1284)

OK, so I am looking for other suggestions and ideas. One thing I would like to do is have a couple areas where I can just plug in some common used stuff like an LCD, SD reader, buttons, switches (probably DIP switches), LEDs (probably just use a bargraph display), etc… Basically stuff that I don’t want to always have hooked up or present. I was actually thinking of installing a microSD slot directly on the custom arduino board and have a dual-row header where I just install jumpers to connect it when I want to use it. I have the board mostly finished and it will include a USB serial connection compatible with Arduino built in.

One idea that I had was to install some common test instruments in there, but I am not going to have room for that. I may have a separate box with a USB hub and stuff like my bus pirate, logic analzer, etc… installed in it. I plan to get a USB oscilloscope as well.

The idea is to have a small, portable development area that I can take with me. Useful for demonstrating prototypes to clients or just tinkering when I am away from home.

Sorry for the long post, but wanted to give some fuel to ideas. I would love to hear suggestions for what other features I should include or common things I should have in there. I will detail the whole project so others can build it.

breadboard 015.jpg

breadboard 014.jpg

In the end, it will be something like the attached photo, but much cleaner and be self-contained. I built that from a cutting board around an Arduino Mega.