Mess Factory

I first started introducing noise into the circuits during my first bicore bread boarding. I found that the steady click of the bicore loop was comforting and that the circuit performance could be easily monitored. By that I mean that influences to the circuit were easily detected when monitored via sound, whereas, previously I needed to stare at the LED's for a long time to discover any subtle difference to a circuit if not dramatically influenced. This led to the utilization of a speaker on a head circuit, using a bicore driving a neck motor with influences for photo diodes. With the head always looking, the sound will change as it approaches and locks onto the brightest light source in view. Other than that, it never said anything comprehensive.
Much later, I met a fellow at a fair, that was doing a little work with robotics and we briefly discussed some ideas. I had planned to find some cheap sound modules and simply hook them up to solar engines (could get a little pricey with the voltage triggers being almost $2 a pop).
I searched on-line to find a well priced sound module. I have a couple at home out of old toy's, but neither got me very far. I came across an interesting site chromaticfield, it had a brief tutorial that didn't look very impressive at first. Later I came across this you-tube clip. That was motivation enough to take another look at the ChromaticField tutorial, because they're using very similar, if not the very same circuit.

First go at it.

It was amusing to me that the 74*14 Schmitt inverter was being used. BEAM robotics wasn't mentioned, but it hit's close to the mark (no pun intended). The circuit requires 3 resistors, 3 capacitors, the 74*14, a speaker and a small solar cell (nine parts... not bad). I randomly selected components, and with two miscellaneous configurations, was able to generate a variety of output. It took about an hour to breadboard one circuit and then solder up the second. Of course, I'm reasonably well set up for this at my home workbench.

About the size of it.

I was a little disappointed with the steady Bzzzzzzzzzzzzzzzzzz I was getting at first. Granted, the frequency of the buzz would increase/decrease with the light level, but I was looking more for a dynamic chirping, not a somewhat steady buzz. The tutorial leaves the last lead of the speaker free to be randomly connected, and it was nice that almost any connection produced a Bzzzz, or some variation of. I'm sure with some different capacitor/resistor combinations, the variety of sounds that could be produced by so simple a circuit would not soon be exhausted.
To form the assembly into an aesthetically pleasing configuration was a little more difficult than I'd planed. Because the circuit is dynamic only when the light level is changing, it implied to me that the circuit must be mobile in some way or another. Otherwise your waiting for sun rise or sun set (or other) to induce the dynamics to the circuit. The first circuit was simply stuck onto a strip of wood to give it a little robustness. The circuit was so sensitive to the light level change that it would noticeably change pitch with the car windows up vs. down, and the windows weren't tinted.

Thought the kids might like it. I did :-)

The next version was to be even more portable, as a necklace. Small though it was, it still made for a big necklace. See "Chip" below. He can stand alone, or be drug around. I formed him up for low light levels. He'll work in extremely low light, but not in medium or high light levels. It may be more accurate to say that it performs at a frequence I can't hear in medium or high levels of light. Even though I free-formed him into a relatively tight package, it still seems fragile. I thought of encasing the whole thing in epoxy, but have trouble committing resources (as usual). I also feel a brittle shell of epoxy (if only a thin coat was used) would offer little protection when dropped and then stepped on. Better to leave it with the fragile perception, then perhaps greater care will follow (yes... I dare to dream).

The all but continuous noises from these circuits is a little much to have around your neck, I think. Some are not so bad, but others sound just like crying or whining, and can be a little unnerving. Even the circuits that sound like crickets and/or frogs can create a very realistic outdoor summer field or swamp feel. The only real problem I've had is that , when it's quiet, I will occasionally hear them when I know it is quiet, almost like a mental echo. Not sure how this happens but it's happened more than once.

Silent Contemplation

At this point, the portable version (Chip) shows some promise, but I'm more interested in the interplay of sounds between multiple circuits. Will they harmonize, or not? One portable circuit is not too bad from a weight stand point, but two or four would be a bit much to carry. The movement is still needed, so I'm considering a hanging mobile as the build platform for the several circuits I wish to harmonize. This requires additional resources. Yeah, mail-order!

Started with a rough idea... and then this.

Finding speakers was more difficult than I thought it would be. Magnetic speakers don't work. At least I have not been successful in acquiring any that would work. Piezo's for the most part do work; although, I did come across several that wouldn't. Also, note that one circuit, once configured can sound dramatically different on one speaker vs. another. This makes it a little more difficult to derive a consistent result from breadboard to solder gun. The 74*14 apparently come in several sizes (regular, small, and micro). I ordered several of each to try out, but the sizes difference could pose a large problem with regard to the solder up. I thought the smaller sized 74*14 might make for a smaller more elegant pendant/necklace. To that end I formed the circuit below. I am finding that a couple of the most difficult things about this circuit are: With so many sounds to choose from, it begins to become difficult to commit to one. Free forming the circuit allows many configurations (not just 2-D PCB), and that is also difficult to commit to.

For ease of soldering, I went the direction indicated in the blue configuration below. The speaker and cell didn't work well with the micro concept.

Small chip test.

Also, note that the sound level drops dramatically with the smaller 74*14 chip. Less mA output :-(

To build the sounds I find pleasing, I'm using two breadboards. I'll find a sound I like and then rebuild it on the second board, where I will make changes till I find something I like better, and then update the first board. Sort of a leap frog approach. I started to take a logical approach and tabulate the sounds for different configurations... Uh... Not gonna happen.

Ignoring the type of speaker used. There are 3 resisters, 3 capacitors, and six somewhat reliable speaker attachment points. Also, at least three light levels to offer dramatically different results (I'll just use 3). If I consider the resisters and capacitors to only be small medium or large: The possible configurations would be something close to: 3R*3sizes*3C*3sizes*6speakerpoints*3lightlevels=1458 combinations. Sorry, better things to do with my time. Leap frog will work for now :-)
I know, someone will say, "some resister and capacitor combinations are the same even though the sizes are different" (whiny voice used here for dramatic effect). Doesn't matter... It's still allot of configurations. The other problem in such a tabulated documentation of the descriptions of sounds produced is a little subjective. So this...I'm letting go.
With three circuits complete and two on the breadboards, entering the work station is becoming more entertaining. Only two will make noise in low light, and it's weak but still noticeable when I enter the room. Then I turn on my work lights and they all get going loud and proud, so to speak. It still brings a smile, much like a warm welcome.

Leap frog sound boards.

Forming a mobile is more difficult that I wanted. It is difficult for me to accept that the hardest part is deriving an aesthetically pleasing solution. Since nothing is perfect, a junky prototype is always better than no prototype...
I started with a solar engine driving a propeller. It's using a solarbotics epoxy-encapsulated cell 37x33mm with SE board on back. The capacitor is 1F and the 1381, J. The idea is that it will wind up the mobile when it activates, and then the mobile will unwind during the next change-up. With a 1F cap. the charge time is about 20 minutes in direct sunlight.

Solarbotics made this easy.

I've formed up two more circuits for the prototype and am still not pleased with the look and sounds. It works, but during firing, will occasionally collide, member to member and could dramatically reduce the mobiles life, if you know what I mean. The collisions occur because as the drive motor fires and starts spinning, the adjacent mobile arms create a drag effect and there is a slight delay before the movement is transmitted. This creates an imbalance, and mobiles don't work too good when out of balance. A heavier mobile structure may handle the input force with a little more stability, but the overall movement input would also be reduced. Will wait to see what the second prototype brings.

Proto 1, ugh ;-P