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Here’s a few more audio bits and a video from the new Phoenix modules:

This first one includes an appearance by the noise generator, some inter-osc FM, both filters, and the distortion/preamp (on the noise, post-filter):

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The next one is the two Nick W. VCOs into the ring mod/multiplier, processed with the MFOS filter and distortion, also includes feedback via an active mult and a mixer channel:

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Up next, we have the same two VCOs, this time each goes to a VCA (each modulated with an Ian Fritz AD envelope), and from there each gets one of the filters. More feedback in this one, I think you’ll notice when it kicks in:

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And here’s the video- same basic patch as the second audio demo above, but different settings:

Due to several things I’ve been wanting to try out requiring it,  I’ve decided to break out the +/-12V power supply I scavanged from my dead ESQ-1 again, and resume work on more modules for Phoenix. My initial thought was to re-house the current 9V modules, and replace them with new stuff- however, I realized that I would soon need more space than that, so I’ve decided to start a second chassis instead.

The first circuit I built for the second Phoenix chassis was a 12dB/oct Sallen-Key state-variable filter (SVF)- there are several variations on this basic design (including the MS-20 and others), the one I built is based on a design by Nyle A. Steiner  (original schematic at Experimentalists Anonymous, Philip Baljeu’s mod/redraw with LDR’s in this e-m thread).  I made a few changes, including changing the gain on the output buffer (it’s now set at 100x gain, well into overdrive territory- but the volume pot allows you to attenuate the signal), and changing the res pot’s value. I think it sounds pretty good, but the LDR’s I have don’t react very quickly, so audio-rate modulation is not possible.

Although I do have several modulation sources available, I decided to build another to go with this filter, just in case they’re all in use elsewhere.  I went with a simple LFO found at the MFOS site- it is essentially the “Super-Simple” LFO, with the diodes and associated resistor removed, and a square output taken from the output of IC1-b. I also decided to go with a single speed range- I went with a 470nF cap there, which gives a pretty good range. There was enough room left on the perfboard I used for the filter for me to build one of these on the same board. I’ll probably build at least one more, possibly with a bigger cap for ultra-slow rates.

Another nifty-looking thing I had recently come across was the Simple Saw VCO (and several other cool circuits) from Nicolas Woollaston at the e-m forums. It works great, so I decided to try to combine it with this saw to pulse converter from the EA archives. This also worked quite well, so I’m thinking I’ll build a pair for this chassis. As of this writing, the VCO/waveshaper is still on breadboard here.

Since it had worked so well with Loid, I decided to try building a +/-12V version of the WP-20 VCA I posted about a short time ago. As it turns out, all I had to change was the op amp- I used an RC4560.This is also still on the breadboard.

What follows is a simple recording of the VCO’s pulse output, being processed with the lowpass portion of the VCF, which in turn is then fed into the VCA. Modulation routing is as follows: the MFOS LFO’s square output is controlling the VCA, and the triangle output of the same LFO is controlling the PWM of the VCO. Two triangle LFOs from Loid are then used to modulate VCO pitch and VCF cutoff.Partway through, the MFOS LFO’s triangle out is re-routed to the filter CV, and the triangle LFO from Loid which was on the filter is in turn re-routed to the PWM.

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Here’s a recording of the VCO’s saw processed with the bandpass portion of the VCF- this one also includes some filter overdrive sounds:

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When I get the VCO and VCA off the breadboard, some AREG’s will follow.

This joystick (a “Flightstick Pro”) was another great second-hand shop find. Opening it up, I found three 100k pots (one for each joystick axis, and a throttle wheel):

My thoughts immediately turned to a 2-osc synth of some sort (each axis controlling one osc), and as I started brainstorming, the idea of a filter of some sort for the third pot came along. My final plan was for the oscillators to be supplied by a CD40106, which would feed two buffered squarewave oscillators into an AM circuit. I chose the TS12A4514 analog switch for the basis of this AM circuit, mostly due to space considerations. The filter is a passive highpass type, using a metal-film 100nF capacitor and the third pot. Each joystick axis also has an offset wheel, which can allow for setting the range of the associated osc, or just act as another frequency control.

Post-op inside photo:

The final product:

Here’s an audio demo:

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…and here’s a short video:

This one is also going on eBay to raise some money for parts. It’s probably the one I’ll have the hardest time parting with, of all the things I’ve built & sold so far. If I ever find another joystick like this, I’m keeping the next one.

Once again, this device is named after its housing- in this case, a tin with a “Smokin’ Joe’s Racing” logo from Camel cigarettes:

Here’s a close-up of the board:

Some of the components for the EQ are mounted on the pots. The only additions I’ve made to the circuit from the last posted schematic is to add a feedback loop from the line output to the switched side of the first input jack, so that the connection is cut when something else is plugged in. This feedback loop allows it to act as a sound source in its own right, even without any inputs.

Here’s what the final build looks like- the camera’s flash makes it look blue in these photos, but as the earlier pic shows, it’s actually purple:

You’ve already heard what it sounds like with inputs, so here’s a quick recording of the feedback loop oscillation:

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Found this thing at a second-hand store cheap- since it’s made out of clear(ish) plastic, I could see a couple of resistors on the circuit board, and thought it would be worth checking out for the price, in case one of them was a pitch control. Score! It was.

Below is a shot (kinda blurry, sorry) of the circuit before bending. The resistor marked “R2″ is the pitch resistor. You can also see the backside of the built-in speaker:

The rest of the circuit wasn’t very exciting, the sound-making part was a blob-type IC. The other possible bend would have been to add external play triggering, but retriggering while it was already playing didn’t interrupt what was already playing, so that wasn’t super-exciting either.

What I ended up doing was taking out the existing resistor, replacing it with a 10k (it was 55k), and adding a 500k pot inline. Here’s a shot of the board after modification, notice the heat-shrink tubing around the resistor for added strength:

I ended up having to add a second 10k resistor to the opposite side of the pot, as 10k wasn’t enough resistance to keep the chip from crashing (easily fixed by cycling the power). Of course, a 20k resistor at the board would have worked too, but I’m fresh out anyway. I also added touch points (using screws) for changing the pitch- they also cause some glitching under certain circumstances, sometimes leading to crashes, which again can be easily remedied by cycling the power.

I also added an output jack (with a 1k resistor on the board end of the wire)- I had to go with 1/8 inch, due to size restrictions imposed by the enclosure. I also had to grind away some plastic which was getting in the way of the jack.

Some shots of the finished piece:

…and here are some sounds. First up, a dry recording, messing with the knob & touch points:

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Next, processed through the LM567 amplitude modulator in Phoenix, then a lowpass filter, and a delay:

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This one is just the Sorry Pawn with delay:

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After trying unsuccessfully to sell my Yamaha Electone 315u-i  electronic organ for a good long time now, I finally decided to take it apart and see what might be useful elsewhere.

The following view from the back shows some of the more interesting parts: a Leslie hookup, a wannabe-Leslie rotating speaker setup (in the boxed-off area in the bottom right), a spring reverb tank, and the main speakers. My initial thoughts are to use all this to make a combo amp.

The next photo shows the power board:

This one shows the microcontroller board, which contains the arpeggiator and auto-accompaniment components- I think at least the sequencer portion of the drum machine resides here too:

So far I’ve also found a couple other interesting things, including an IG02610, which is the same filter chip used in the CS-01; and several MN3006 chips, which are digital BBD IC’s designed for use in modulated-delay-based effects such as chorus. None of the IC’s are socketed though, so it could be tough to remove them from the board(s) without damaging them.

The stops and other lever controls all use Alps pots, though all the stops are stepped, which will make them less useful. Plenty of wire in there though! The keys and associated circuitry could also be useful.

The same dead guitar amp from which I had recently harvested a number of pots and dual op amps also contained two CD4053′s (well, one was an equivalent with a different part number, but still…). After getting Loid transferred to the new container, I had stuck one of these on the breadboard for playing around with, and finally got around to putting it on perfboard to become a permanent addition. This is another module which is just wires going right to the pins, and fit perfectly on one end with 4 rows of 3 screws (control inputs A, B, and C, which switch the X, Y, and Z in/outs between two other sets of X, Y, and Z in/outs- I chose to ground the inhibit pin).

Here are a trio of recordings made with the 4053 in various combinations with Loid’s other modules:

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My friend Kris recently gave me a couple of old joysticks, the first of which I’ve modified to be used as a CV controller.

The photo below shows the inside of the joystick, before any modification:

As you can see, the X and Y controls are actually slide pots (150k linear, to be precise). Using the bottom pot in the photo as a reference, the far left pin is the wiper. The first thing I did was remove the PCB and the PC connector cable. Then I drilled holes for the jacks, and wired it so 9V comes in via a 1/8″ switched jack, and goes to the far right pin, and it’s equivalent on the other pot, with the middle pin going to ground to form a voltage divider. Since I used a switched jack, I could also make it capable of running off a battery for portable control of stuff like the Modutronic Messmaker.

Here’s a video of the joystick in action with Phoenix:

I have plans to also add some internal LFOs which could be switched in with the buttons, but this is definitely a fun start!

An R/2R ladder is a simple circuit, often used as a Digital to Analog Converter (DAC). There is a good introduction and how-to guide here.

Here’s the circuit on perfboard (the op amp is an LM358):

It may not be immediately obvious how such a thing might be useful in a noisemaking device- I know it wasn’t to me. They say a picture is worth 1,000 words, so here are some screenshots from s(M)exoscope… the first one is a shot of 4 of Loid’s oscs, roughly tuned with two at one frequency and two at twice the frequency:

…and here’s a couple with them completely detuned:

Here’s the obligatory audio example- this is just those same four oscs being fed into the R/2R, whilst I twist knobs:

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After posting about the Switchgate at Deathlehem, the always-helpful Rich suggested a method for extracting a short pulse from an incoming signal- see the thread here. Though that original suggestion didn’t work, it got me headed down the path of breadboard experimentation that led me to this:

I added two of these to the same board as the R/2R:

Switchgate is a simple dual gate based on a 556 in monostable mode (with trigger input), with the monostables triggering two switches. The monostable outputs are also accessible via their own outputs.

Here’s what half of it (a single monostable/switch circuit) looked like on the breadboard:

I put a 4019 quad AND/OR select gate (wires straight to pins) on the same perfboard with the dual gate VCA, and put them in an old external modem case:

I’ve also added a 4051 multiplexer wired straight to the pins to the Melody Generator/ring mod can.

Here’s a recording of the Switchgate/4019  in action with the other modules- the Melody Gen and 4051 were left out:

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