Last night El MuCo (The Mutagenic Cooptoraptors) accomplished a feat heretofore unimaginable: three circuit projects were undertaken and three projects were completed successfully. While you may be tempted to think that, with the assistance of a book (Ray Wilson’s Analog Synthesizers) and the vast power of the internet this is not a big deal, you could not be more mistaken. Not only because of our chronic electronic ineptitude, but because even getting all the parts together for this much electronic awesome is daunting. Of course, we didn’t have all the right parts, but we did it anyway because SCOFFING AT CONVENTION IS OUR BREAD AND JAM™!
[Side note to kids: don’t scoff at convention by rolling with the wrong components. Only sadness awaits you. Seriously. We are pros.]
Now, lets have a look at the goodies and learn us a thing or two. (Well, learn you a thing or two — we already learned our two things. And forgot one of them.)
Square Wave Oscillator
This oscillator came from the Wilson Analog Synths book in the back, op-amp circuit section. Our values differ a bit, and, of course, we added a voltage divider.
Tricky? Not really, but if you aren’t getting the results you think you should check your virtual ground. If the virtual ground isn’t setup correctly because 1) the caps/resistors are in the wrong config 2) are the wrong values your output will be decidedly different than what you expect.
White Noise Generator
It works! And it’s simple. What more needs be said? The configuration is really straightforward, it only requires a few components that are easy-to-get, and gives you that sweet ear-damaging white noise you have been craving since your TV went digital and no longer wakes you up with horrifying noise when you fall asleep in front of network TV and the local station goes off air at 2am.
Tricky? Nothing tricky.
It works, sort of! <– what more can you ask? I’ll tell you what more, voltage control. The above is a really simple low-pass filter configuration whose cutoff is controlled by a couple of capacitors. [EDIT] Because this post was sitting in “drafts” for a month, I’m happy to report we have made more modules and started work on the VC filter. More on that soon…
Shameful admission: the above LM386-based amplifier is the first such circuit I have built that has worked. By worked, I mean it provides a sufficient amount of gain while not introducing unwanted noise. I think, but I’m not sure because I dismantled them all, that the problem with my earlier attempts to make this circuit was that the cap shown above running in parallel to the audio signal was not of sufficient voltage. Or it was gremlins. Or a cosmic convergence.
All of the above modules can be strung together in various ways and powered by a single 9v battery. (Note: if you get your 9v batteries from IKEA because you are cheap like me, you can expect your 9v battery to have about 12v out-of-the-box. Be warned.) AFAIK, power to the rails of each component can be common and can enter the circuit (collection of connected modules) anywhere. Fun times!
We have completed another couple modules in an effort to prototype all the modules in the Wilson Analog Synths book. I’ll post again as soon as we have the VC modules and the amplifier working in concert.