circuit bending

Weekend events in San Francisco (Music, Art and Cats)

Another busy weekend, especially with the number of things going on. We only have time for a partial review…

First, there a quick stop at downtown pub to see some friends/colleagues. Then a rush to BART to get across the bay to Berkeley and my old stomping ground, the Center for New Music and Audio Technologies (CNMAT).

I was a few minutes late, but still had plenty of time to hear Joker Neils and Gino Robair performing a improvised duet. Robair has an amazing talent for getting electronic-like sounds out of acoustic percussion instruments, and did so again on this evening. Neils was primarily using custom synthesizers, both professional instruments as well as circuit-bent toys. We have discussed circuit bending previously here at CatSynth. He brought several well-crafted examples, including Suziki Omnichords with contact-resistance interfaces; and he also brought a tremendous enthusiasm to his performance and to his discussion of circuit bending in between sets.

Also presenting was Rob Hordijk, who designs custom synthesizers (or “works of art” as he described them). Among the technologies he employed in the “Blippobox” that he presented were chaotic oscillator pairs, where two oscillators feed back into one another to create non-linear modulation, and a filter that he called the “twin peaks” filter (presumably because it has two resonant peaks).

Amy X Newburg lent her vocal and electronic-music talents during the presentation and in the second half of the show – readers may remember her from a a recent music festival that we reviewed.

I had some interesting conversions with both Amy X Newburg and Joker Neils following the performances, which is always a nice coda to a concert.

It was another exceptionally warm weekend in San Francisco (I wouldn’t mind it becoming less exceptional), so more opportunities for walking events. First off I finally made the trip to the San Francisco SPCA to inquire about volunteer opportunities and see their much touted adoption center. The cat area featured large rooms, “kitty condos” as well as comfy areas to hide – it actually seemed on par with the “cat resorts” where I looked into boarding Luna. The SPCA is actually a short work away from CatSynth HQ (well, it’s at least short from my perspective).

Another short walk in the opposite direction from CatSynth HQ led to the Yerba Buena Gallery Walk. Open studios and gallery events are pretty regular occurrences, even within walking distance. Plus, there’s often free food and drink. I didn’t see too many things that truly interested me, except for some abstract paintings at 111 Minna that I had already seen during the first Thursday earlier this month. But that doesn’t mean the afternoon wasn’t without its attractions. Some of the galleries, such as Varnish, were in very interesting spaces, such as converted industrial buildings from the early 20th century. A view of Varnish is in the photo to the left. Additionally, some of the sights on a gallery tour aren’t the works of art, but the people viewing them – and this is even more true on a warm sunny day. Finally, I did have a delightful conversation with Jesse Allen at Chandler Fine Art – his very psychedelic/natural works aren’t what I am usually drawn to, but some of them did include abstract representations of cats and other animals and one “wild cat” in particular caught my attention.

More art on Sunday, this time photography. This Sunday was “Pinhole Photography Day” (who knew?) and the RayKo Photo center featured an exhibit, demonstrations, and most notably a ride on the Bus Obscura a school bus converted into a large camera obscura.

The bus obscura toured our South-of-Market neighborhood, providing a unique view via the pinhole-camera images. Small dots of blurry light would suddenly come into focus as a sidewalk or car or storefront.

Because the image were so localized, it wasn’t always clear exactly where the bus was, though every so often a familiar landmark would emerge. The ride was accompanied by live acoustic and electronic music, adding to the experience and making it different from the regular “tours” of our neighborhood.

CatSynth pic: kittennettik fyrall

It's been a little while since I've posted an actual cat-and-synth photo. Here we have a kitty posing with a “kittennettik” instrument called the fyrall. From the website:

fyrall is a multo-jungo-world dialer, it is a freak. Within, it has three electronic wheels, one made out of wigglers, one made out of digital counting temples, and the third reconnects the others. at every move it may be in a state of internal paradox. it is always looking for a state of rest and it can never find it. Experimenting on the fyrall is fun because new rewirings will cause it to spasm in the weirdest ways.

The fyrall and the other kittennetiks use chaotic cicruits for sound synthesis and control. The creator of these instruments has some specs and papers, which are, well, quite interesting. See for yourself.

My interest is definitely piqued. However, I might try looking at one of the “paper circuits” they provide before considering any of the full-blown kits.







catsynth pic: Reed Ghazala Tape Canvas Device

I was reviewing Get LoFi for yesterday's circuit-bending article, and came across a reference not only to Reed Ghazala, whom I also referenced, but a catsynth pic to boot!

Who knew the “father of circuit bending” was also a cat person? Then again, perhaps I shouldn't be surprised…

The tape canvas (illustrated above) itself is interesting as well, allowing expressive control of a device and process that is traditionally linear. It inspires me to revive my interest in musical reading of barcodes using a CueCat, which has the added advantage of continuing the feline theme.


The CueCat has proved a difficult device to work with, however. I have a modified version that gets beyond some of the proprietary issues and shows up as an HID device that can be read in OSW, but I have yet to make it work properly.

Adventures in Circuit Bending: Vtech Tiny Touch phone

Last evening I embarked on a circuit-bending project, and this forum provides me a unique opportunity to document the experience.

For those who are not familiar with circuit bending, it basically the process of modifying the electronics in existing audio devices, usually simple analog circuits in musical toys. In the process, one can add new expressive controls to create a unique, albiet “lo fi”, instrument. A great introduction on circuit bending can be found at Reed Ghazala's Art of Circuit Bending. Additionally the blog Get LoFi has a wealth of information and circuit bending projects and instruments.

This experiment involves the Vtech Tiny Touch phone. It plays a few simple phrases relating to numbers and colors as the buttons on the phone are pressed. You can listen to an example here. Vtech toys are good circuit-bending fodder, and I've tried the phones before. During my first attempt, I shorted out the integrated circuit (oops), which ended that effort. The second time I did a simple bend across a timing circuit that allowed me to alter the speed and pitch of the sound with a potentiometer. I had this instrument open for kids to play with during the my show at Zeum in San Francisco this past spring, which turned about to be a death sentence for it. One kid happily showed his parents and me the capacitor he managed to pull off the circuit board. This time I'm going more slowly and methodically, with the goal of a more interesting and robust instrument.

First, we open up the phone to reveal its guts (i.e., circuitry):

Now grab a test wire (i.e., with clips on the ends) and start looking for interesting “bends” by shorting different points in the circuit. In general, this is a hit or miss process and experimentation is the rule of the game. However, care should be taken to avoid shorts that could damage the audio circuits. In particular, stay clear of anything that connects directly to the batteries.

A rather effective short is opposite corners of the IC board, as illustrated by the pink dots in the closeup below:

Shorting these leads, which essentially drops the resistance to near zero, slows down a timer and thus the speed and pitch of the audio, as can be heard in this audio clip. Note the slower version of the telephone ring. From this result, one can conclude that varying the resistance changes the timing and pitch of the sound, in particular highwer resistance yields higher pitch, with infinite resistance (i.e., open circuit) restoring the original behavior. Such a bend is a good opportunity for a potentiometer to mechanically change the pitch, or a photocell to use light as a pitch control. For now, I am attaching a photocell using alligator clips:


Cupping my hand over the photocell and moving it closer and further while pressing buttons yields variable-pitch sound and beginnings of a new circuit-bent instrument.

I could stop here and make this bend permanent, but I would to continue with other options, including switching between photo, mechanical, and null modulation, as well routing other signals over this bend to create FM synthesis. I will continue to document this project here as I find more time to work on it.

Actual Cat Synth

jfm3 of Ouroboros Complex posts about as literal a “CatSynth” pic as you can get, featuring his cat Kona and accoutrements as part of his rig. Cat aside, the rig and website include a wealth of personal experiences with analog synthesizer hacking as well as circuit bending (note the mod'ed Speak&Spell). Please give jfm3 and Kona a “catsynth welcome” by visiting their site.