Week 10: Output Devices

This week we are tasked with ouputting something. We are assigned with the task of designing a microcontroller board that uses output devices.

What to Make?

Some ideas for this week are

• Charlie-Plexing LED example
• Stained glass light box with LEDs inside

Here are the steps:

I read once that the key to a long and happy life is unfinished projects. At this rate I'll live to be two hundred and forty.

Stay Awake

Design Board in Eagle

My schematic in Eagle

My components in board view in Eagle

My wired board in Eagle

I learned to add wires and outlines on different layers

The top layer in Eagle and exported for design

The bottom layer

The vias

This week I used Neil's example to design the charlieplexing 2 sided board in eagle. This took a very long time. I knew I wanted to vinyl cut everything so I beefed up the traces and tried to avoid traces running under the microcontroller or too close together. I learned how to add items on different layers in Eagle- First click on the layer then click on the wire. I learned how to change my font in eagle and how to add a board cutout outline in the documentation layer (51) that you can export and use as your board cutout outline. I don't yet know how to get components on a separate layer but will Google this and post results soon.

Added additional solder jumpers (0 Ohm resistors) so I wouldn't need to run as many traces under the microcontroller.

I talked to our TA Rob and he said it would be easier to start with a 1 sided board so I also designed a one sided boad using Neil's templates. This also took a very long time.

I also experimented a bit with painting traces and researched conductive fabric and paint for future projects.

Vinyl Cut Board

Loaded up my png in fab modules and adjusted the settings slightly. A force of 47 and a speed of 2.5 with a pen force on the machine dialed at .5 worked well. I also adjusted the tool diameter to a lower setting to get traces spaced farther apart.

Neil said every year peole fall in love with the vinyl cutter and do everything on it. I've been trying to fall in love but it's been very difficult. This week the vinyl cutter and I had a very good 4th date. Not sure if it is true love yet but it is definitely promising. I decided to try vinyl cutting the board again because I am a glutton for punishment. I adjusted the pen force, speed and the depth pen was sticking out of the vinyl cutter. I began to cut and things appeared to be working well. When designing my board I didn't design any traces under the micrcontroller because this is where things were ripping before. I also increased my traces to 36 mills where I could and spaced components fairly far apart. I also changed the tool diameter size in the fab modules to be less than the standard setting so the traces would be even wider when they cut out.

Weed The Board

This took a really really long time. NOte if this step is really painful and taking too long your traces may be too thin.. OR your vinyl cutter may not have actually cut all of the way through- If this is the case you are better off cutting again and starting over. I cut out some pads and traces and used previous boards to repair broken traces on the final board after it was weeded.

It is easier to weed if your cutter has actually cut all of the way through

A few of the traces ripped up and were lost in the wedding process so I used the cut vias to replace pads and traces from previously cut boards to patch and repair the final board.

Gather your parts

I gathered my parts and placed them on the double sided sticky tape with a label.

Stuff and Solder the Board

I wanted to use lead free solder for my circuit so I found some lead free solder in the bin, turned my soldering up to 825 and soldered away. It was not much worse than regular solder! This part was a bit tricky with the vinyl cut traces. I guess the adhesive on the copper is really sensitive to heat so whenever I'd heat the traces to solder them they'd move and squirm around. This was very frustrating. Also flooding a component with solder and then sooaking it up with the copper braid didn't work well AT ALL because the traces moved all around when I was soaking things up and melded together. The connections to my microcontroller look very messy and hideous. Also the plastic substrate I'd mounted the traces on melted so I ended up affixing it to a piece of glass. Next time I'd use a different substrate or just weed directly onto the glass. I ran out of lead free solder with only three 0 ohm resistors left to solder. Very disappointing. Really want to finish this soon to test it out.

Program the Board

Coming soon

Check all connections

Stay Tuned

Finish Soldering

Coming soon

Debug Board and Program to light up!!!

Coming soon

Results

• Nothing works yet
• This makes me very sad
• If I had a circuit that measured sadness my results would break the circuit
• Add real results here when I get my board to actually work!!

Tools/Materials Used

For designing:

• Eagle
• Photoshop

For Making:

• Vinyl Cutter!!!!!!!

Materials:

• copper boards
• components
• copper adhesive
• hot glue
• copper paint, copper foil

Lessons Learned

• Make sure your vinyl cutter cut all of teh way through your component before weeding
• Be meticulous about your design. Ensure all connections are properly made.
• If you want to vinyl cut keep your traces large... keep a printout of your intended design so you know which components you need to repair
• Flooding a component with solder does not work when soldering a vinyl cut circuit
• Solder faster
• Spend extra time pressing down your traces- the ahesion will matter later
• The sticker substrate doesn't work well. Use something else
• Your traces may move around a bit when you solder- if you can design your circuit with a bit of wiggle room so you don't inadvertantly create a short
• I make things harder than they have to be
• The voltmeter is an excellent tool to trace paths and connections
• Things are easier to figure out when you're with someone experienced.
• Hot glue can fix a lot of things but sometimes you're better just starting over.

Conclusions

• Get healthier, Start earlier.
• Even if you've done something before it doesn't mean you won't make new rookie mistakes
• Designing a circuit well, even a simple one is harder than it seems.
• Time is the only real commodity in life. Spend it wisely.

Next Steps

• Recut board
• Stuff and solder and program board
• Make board actually do something
• Weed vinyl cut board directly onto glass and make glass light box, investigate conductive paint, thread and fabrics

Files

Copyright 2013 Kathy Sinclair