Circuit Board for Making Freeform Circuit Sculptures

Intro:

I find that working as an electrical engineer in a professional environment causes you to think about electrical design differently than you might in the makerspace. You learn how to do simple designs really quickly, but also have to consider a number of variables you wouldn't need to when just doing it for fun, such as signal integrity, accuracy of voltages, and the list goes on and on. I've been looking for ways to get more creative in personal engineering projects, and recently discovered the art of freeform circuit sculptures. This artform is actually a little difficult to get into if you haven't tried, so I decided to make a platform for lighting some LEDs to start with while I improve my ability to solder brass and copper wires.

Equipment:

- Soldering Iron

- Solder

- File (to file down the brass wires)

Parts (Per Board):

8x - 22uF capacitors (can be larger)

7x - Transistors (2N3904 is fine)

7x - 33kOhm resistors (can be changed based on capacitor)

7x - 220Ohm resistors

1x - Button Battery Cell Clip

1x - On/Off Switch

For the Sculptures:

7x - 5mm LEDs

- Brass wire or copper wire

Making a clean intuitive and readable schematic is always a goal of mine. In industry you might end up with a 20 page schematic that you have to understand and give feedback on within a day. The easier to read, the better the feedback.

Of course the function of the circuit is important too. I wanted this to be an accessible project to anyone with a kit of basic electrical parts that they probably already have on hand. This relatively simple circuit is a multi-vibrator that will make up to 7 LEDs blink in a variable pattern. The timing of this pattern can be modified with different capacitor and resistor values, and pretty much most basic power transistors will work for this application.

Finally, the headers on the board provide the connections for the LEDs. This is where we can get creative and make a wire sculpture lift off the board.

Layout design definitely gets more complex in the industry than it needs to be in the makerspace. In a design like this I don't really care about noise and capacitance between signals on the board. I don't care about having thick copper traces in a design like this because there's not a whole lot of current, and because I want it to be easy to put together, all of the main components are thru-hole and sit on the same side (except for the battery clip).

I tried to be clever by adding what I'll call two "leg breakout boards to the sides", but I found that this idea didn't work so well and I did some other modifications to make it stand up.

So I didn't like how circuit worked when I first plugged in the LEDs. I found that they turned on and off really fast, so much so that you couldn't tell they were turning off and on. To counteract this I decided to model this in LTspice. It's free and easy to learn and play with. I used it to figure out some new resistor values that I liked (33kOhm in this case) to replace the 10kOhm resistors tying the transistors to the power rail with. This directly effects our RC time constant by increasing it, making the lights turn on and off less frequently.

I would be more than impressed with myself if I ever did a project perfectly the first time. There's always room for improvement, but in the industry people don't always need it or want to pay for it.

Most of the soldering went smoothly, but I did run into a few issues. In my case, I didn't like how small the transistor footprint was. I think it would be easier to solder if the pads were a little farther apart from each other, and maybe a little large. I also messed up by allowing the thermal reliefs around the ground pad to be too thick so they we're hard to heat up.

As far the "leg breakout boards" go, they were a little too difficult to get off of the PCB without extra tools (whilst I intended for them to just break off), and I didn't like how the clearances turned out that much with it actually standing. That said, this is how you learn. Next time I'll put more effort into this section of the design should I make a similar device again.

Brass wire tends to look really good in circuit sculptures. It also happens to be more difficult to solder to than regular wire/a circuit board. Copper wire also looks good, but tends to be softer and easier to accidentally bend. Of course, the copper wire is easier to solder, so for making your initial ideas it might be easier to start with the copper and get your design down.

My first try look didn't come out too bad, but if you look closely you can see where I didn't do a great job soldering to the brass. I've learned that some of the solder and flux used in circuit boards isn't that effective at making a good bond with the brass. I've also learned the importance of having a template when it comes to bending a wire.

However, it did look pretty cool when I finished it. After having taken the time work out some of the problems I encountered in the first version I made another sculpture that I think looks a little cooler! I attempted to make a dog... it's not that bad for the first try, but I realized after making this that I don't like using LEDs for eyes. But that's how you learn.

My key take aways for soldering brass wires are making sure you have a good heat source, making sure you have a rosin core and thick type of solder, and making sure you file or sand down every surface you want solder to go onto.

All in all, I'm initially satisfied with the end results. Here's a video of first one I did operating. For the dog looking one I left a few LED paths disconnected, so the lights don't blink but remain on.

I hope this inspires you to try out a new artform, do ECAD, modeling, and circuitry!

You can download all of the files I worked with here if you're interested.

I've also included the LTspice model I was working with in case you're curious.