There are a ton of uses I can see in having easy access to the radio waves: random noise, strange sounds, fuzz and white noise.

But being able to control the tuning with CV so I can jump around the dial, or slew my way from one spot to another I think would be really awesome.  If for no other reason than I like the idea of programming up a sequence and then every time it runs it will be different since the sound source is constantly evolving and changing.

So research began by looking at how radios work, and things didn’t look good to start off.  It seems that radio tuning is all about capacitance, not voltage.

The simplest tuner consists of an inductor and capacitor connected in parallel. The capacitor is usually made to be variable (although the inductor can made variable it requires a more complex mechanism and is rarely used). This creates a resonant circuit which responds to an alternating current of one frequency

http://en.wikipedia.org/wiki/Tuner_(radio)

This means “most” of the time the tuning pot is not a pot but a variable capacitor type thing, which means you can’t just swap out the pot with a CV source (which was my initial hope, ignorance is bliss).

All seemed at a lose until I found out that some radios use what is called “varactor diode tuning” this is a diode that in essence replaces the capacitor bit, but the neat bit about the diode is that it’s voltage controlled.  This means that the tuning pot will be handling voltage and suddenly we have somewhere we can bolt our CV into.

The next snippet of info, was that Ramsey (the makers of great electronics DIY kits) make a series of kits that all use Varactor Diode Tuning, include a $40 FM receiver kit.

So later part of 2010 I ordered one up, and it sat on a shelf for a few months whilst I tried to finish off other “higher priority” projects.

Then NAMM 2011 came around, and I was intrigued to see that Buchla, the makers of VERY high end modular synths was showcasing a new module the 272e which had 4 FM receivers that could all be referenced via CV.  Now their concept is very different to mine, they have digital tuners that you tune and they then allow you to control the outage from each using complex envelopes, there is no CV control of the tuning – that said they do look really very nice indeed.

Buchla patch Model 272e through the 296e Spectral Processor. from Richard Devine on Vimeo.

But if nothing else it spurred me back into life.  So earlier this week I soldered up the Ramsey kit.

With some awesome help over on the muffwiggler forums (MANY THANKS DAVERJ!)

I tapped into a couple of places on the PCB and hooked it up to a very low frequency Oscillator I had running a sine wave, and low and behold I had CV controlled tuning.

Now the tricky bit.  I doesn’t work great. It doesn’t work with CV only with the Oscillator, so it needs a stack load more tweaking and testing.  But my hope is in the next week to get it hooked up to Silent Way and have a fulling CV tunable radio incorporated into my modular synth.

I’ll post some code and details of how it’s setup later tonight when I get home.


int signalPin = 8; //servo signal pin

Some useful reference sites, but be aware that neither of these I could get the code to work, but probably more my issue than the code:

http://principialabs.com/arduino-serial-servo-control/
http://itp.nyu.edu/physcomp/Labs/AnalogIn

Next step, aiming low, I want to get a button in max that will trigger the servo movement:

http://www.cycling74.com/forums/index.php?t=msg&goto=165203

Once I have that, I just need to replicate the action with the 6 other servos, work out how to attach hammers to them all, and then add some sort of step sequencer in max so I can have a 6 note analog drum kit.... that is until my xylophone arrives.

Finally found some time in between flu forced naps to finish off the display portion of the knobome idea. Now all I need to do is stuff this into the small looking enclosure I have and then work out what I’m planning on doing for an input. LyodMilligan has some very promising ideas over on the other post. Although he very quickly got me out of my depth in terms of technical know how, so I’m hoping he’s going to throw me a lifeline before I start drowning. I also suspect I might run out of room. For that reason I’m thinking I might go with a simple 2 x 8 position rotary switch and a small momentary switch.

Twist the 2 rotary switches to the 8×8 co’ordinates you want and press the button to trigger a press.

I should be able to get away with that with nothing more than some imaginative wiring and no additional components – but we’ll see.

Then I might approach the knobome enclosure slightly differently.

Original inspiration for the knobome is the orange keypadless monome (except if I’m correct Tehn’s has no monome input, other than maybe ADC or ENC), video of his in prototype.

Update, it took a great deal of trimming, pushing and bending, but it’s all inside the enclosure now. Absolutely no room for switches or knobs. So this one will become a viewNome. Knobome will need a bigger house.

My issue wasn’t with the shield soldering or my pin selection, is was that I’d stupidly used Arduino v12 to compile and upload the firmware, and as we all should know by now, that won’t work, you need arduino v11.

So I was able to crocodile clip a couple of pins as per Unspeds response on the forum…

IN
15,13,11,09,07,05,03,01
16,14,12,10,08,06,04,02

OUT
02,04,06,08,10,12,14,16
01,03,05,07,09,11,13,15

(the positive side of the led’s to the SEG pins on the max72xx chip)
connect led matrix pins: 5,6,7,8,9,10,11,12
to arduinome pins 2,4,6,8,10,12,14,16 on the “IN” connector

(the negative side of the led’s to the DG pins on the max72xx chip)
connect led matrix pins: 1,2,3,4,21,22,23,24
to arduinome pins 2,4,6,8,10,12,14,16 on the “OUT” connector

Now I just need to find a nice solution to wire up to the led matrix, I think I’ll end up just soldering directly to the matrix a pair of ribbon cables.

Now once I had my matrix working with the test, I fired up monome_test to see out of curiosity what would happen if I wired one of my potentiometer between the two pins that used to be wired to a button. Well stuff happened, not really what I want, but it was interesting. I’ll take a video and post it over the weekend – not easy to explain.

Suffice to say I need some ideas for plugging 1 potentiometer per row and getting full left to full right equal 0 – 8 column button presses. Any thoughts?

Unsped Shield Parts.

LED Matrix from Sparkfun, and 8 pots.

The idea is to use the OOTB unsped shield. Wire the LED side of it to the matrix, which I am assuming should be fairly straight forward. Then find a way to wire the 8 pots so that each one controls a row with the full left to full right turn being equal to columns 1 – 8.

One issue I’ve already thought of is the serial is expecting button press and button releases, the pots can only register a single value, unless I can find some way to “fire” an on/off signal, this might need a tweak to the serial (which may or may not (I expect may) be a show stopped for this project).

The wood is a little dinged, and I’d probably say that the plywood base makes it look very prototype, but it’s an enclosure and that’s really all that matters right now. All I need to get the project finished is my type-A to type-A usb cable (due any day). Then I can start playing with this some more.

When we first put it together we used the full height of the side wood, so it was about 1.5″ higher than it needed to be. I just trimmed it down an inch, but it seems that with the height of the inside panel and the headers and idc cables I’ve not left enough room for it to fit.

So I’m left with two options. This weekend, I either cut a new box – which now we have the right tools and a first pass shouldn’t be too difficult, or I stop using the Unsped shield in it’s mounted format and try and find some connectors so I can have them side by side. I think I’d rather do that – it’s just a matter of finding an easy way to do the connections. If that fails I’ll cut and glue a new box, ready for spraying.

The box is currently 3″ deep, so I’m thinking of trimming an inch off the bottom to reduce the height. The aim is to spray it with a non slip black spray I found – which seems to very closely match the finish of my black mac book which it will be paired with. Combined with the black faceplate and bright blue LED’s I do have to say it’s rather dandy looking.

My next step is to start working out which apps I need, and start familiarizing myself with them – so expect a fair amount of 101 style write-ups and walk thrus over the next few weeks.

In parallel, I think I might start soldering the second 64 set I have, but in a 4×16 arrangement.

I’ll get some pictures of the box tonight.