Enneatronic Spectralizer

[PHOBoS]

RingMad wondered how I achieved the fading on the audio for the Enneatronic Spectralizer so here's
the schematic and some extra info for those interested.

THE ENNEATRONIC SPECTRALIZER


The Enneatronic Spectralizer is a drone box containing 9 tunable squarewave oscillators with a
simple, 1 transistor, VCA section to fade the sound of each oscillator in and out. The same oscillators that
control the VCA's also control 42(!) LED's, arranged in such a way that it creates a constantly changing
display of symmetrical patterns.



thanks for posting that pic richardc64


The oscillators are all made with a CD40106 (3 chips in total) combined with some resistors, capacitors and
transistors to create the fading effect for both sound and LED's. Values were selected by means of experimentation
to get the result I was happy with. So if you want to use the circuit with a different supply voltage you'll probably
have to change some values. The fading of the LED's also varies with the kind of LED's used, so this will need
some experimentation aswell.

Each group of 3 oscillators (build around a single CD40106) also has a switch to turn the sound off. This makes
tuning a bit easier but can also be used to switch between differently tuned drones. The tuning itself is done
with a 47K pot (fine) in series with a 250K trimpot for pretuning (coarse). Originally the circuit was made with
just the 250K trimpots, but it was difficult to tune them pecisely so I added the 47k pots in series and
pretuned them to a low, mid and high section.

The sounds of the oscillators are mixed together with an opamp and then send out to a jack, which is wired up
in such a way that it can also be used as an EFX Send/Return for the build in amplifier. The amplifier itself is a
very basic LM386 setup. The 65Ω speaker was just something I had laying around that was small enough, so it
doesn't have to be 65Ω.


some extra info on the display:
- directly in front of the LED's there's a layer of frosted plastic to diffuse the light a bit. (cut from a box that came with some VHS tapes).
- on top of this is a blue lighting filter to dim the lights. (42 bright green LED's produce a lot of light! )
- followed by a green lighting filter which together with the blue creates a very nice shade of green.
- this is covered with a piece of perspex to protect it which also functions as a mirror if you turn the LED's off (bonus effect).

because there is some space between the LED's and the plastic it creates a sort of 3D effect were the brighter LED's
seem closer then ones that are dimmed.
(I added a photo which shows this a bit)


You can find a audio recording of the Enneatronic Spectralizer here

or watch this video to see it in action:

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[RingMad]

Wow, PHOBoS, thanks for all that documentation! So very generous of your time.

And let me say, because I'm feeling it strongly right now, that I love these DIY forums here on e-m... so inspirational and educational and fun and it keeps one going knowing there are other people spending hours soldering up crazy projects that most people would not understand the point of.

James.

[JingleJoe]

This thing is great ... I was just hypnotised by it for about 5 minutes.

[PHOBoS]

[dirtyworm]

Thank you for sharing this. It is helpful as I have been working on a vca type of circuit for my Lunetta and this is proving to be helpful in getting points that I was struggling with working to my liking.

Very cool housing you have created on the last few projects, the LED display on this one makes it that much more interesting.

[PHOBoS]

Thanks, and great to hear it's helpful

[analog_backlash]

[nathanxl]

This is really great.
I am hypnotised by it.

Id love to know/see more on how you layed out and wired up the LEDS to the VCAs. It truly is a fantastic effect. The orientation and fade rate is just superb.

Impressive

[Draal]

Frickin' awesome

[Blue Hell]

Finally found time to listen & watch, lovely box!

[PHOBoS]

Thanks a lot guys!

[Ganzha]

Thank you very much for your Magic Box! that is really excellent!!!!
I am impest!!!!

[PHOBoS]

Thanks Ganzha!