DIY Ribbon Contr.: using CP-251 to attenuate 10v CV source?

The Moog Forum Moogerfooger Forum
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I’m going to try to put together a basic ribbon controller with just a bare-bones circuit, as seen here: http://www.paia.com/ProdArticles/dual-ribbon-howto.htm. Perhaps some of you have already seen that or built one yourself. I have never built a circuit or learned how to read schematics really yet, but I have a growing knowledge of electronics, most of which has been gleaned from messing with Moogerfoogers and analog synth emulators (soft-synths are good little learn learning tools). I have a friend more experienced that can help me out with electrical know-how, a multimeter and any math that may be needed.

Basically though, I take it the schematic is telling that in the first circuit, it is powered via a 9v battery? If that’s wrong I’m on the wrong track. As I read that page, it said the lowest voltage on the controller is 0v, 5v in the middle and 10v(?) at the top. If I am correct about the 9v battery, can I use the attenuator on my CP-251 to bring that top voltage down to 5v? If not, is it only for signals are already in the 0-5v range, for use to attenuate them further than that? I know I can damage and I think destroy parts of the circuits if I put more than 5v in there. Costly Moogers, and I value them very much.


If it helps anyone to understand what I plan to use and connect with this ribbon controller here it is:

Ribbon controller>attenuator [cp-251]>Freq. control on Mf-102
Carrier/osc out of MF-102>lag [cp-251](to transform a sine wave into saw wave)>Mf-101>amp or other effects

Thats the basic idea, thanks for any insight anyone might have on this.

Extra question to those knowledgeable about DIY ribbon controllers: Can I use 1/2" reel-to-reel tape as the conductive element? I have a garbage bag full of spliced tape that was gathered during the editing of my band’s last album. I plan to use a guitar string for the probe as described in the Paia guide; I have an abundance of them. I got the idea from a youtube video, not sure if it works for all tape though.

Edit: As I was reading, it occurred to me that really this thing can be like an expression pedal. If I hooked up the ribbon to a TRS cable, could one of my Moogerfoogers just power it with the correct voltage, and thus no attenuation necessary?

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The ribbon controllers I have had the most success in building were made with S-VHS tape, which is really hard to come by, and expensive. The second element I used was a guitar string, and the whole thing was covered in duct tape…very crude and unreliable, as the tape wears out after only a few uses. These guys build relatively inexpensive and good quality ribbon controllers http://www.psionicsoundworks.com/ and elements can be purchased at mouser.com, or at least, they used to have them…don’t know if they are still there and my brain can’t recall the actual name of the component. :blush:

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thanks, yeah i would love to buy a walking stick, i’ve been wanting one since last year, but every time i feel like buying one I don’t have any money. My ribbon controller will be crude but effective. Did the duct tape wear out or the SVHS tape? I tested a bunch of regular VHS tape and a couple tapes are good to use. Neither my 1/2" analog tape or 1/8" digital tape had any useful conductivity.

I figure I’ll wire a TRS cable for power as I said in my edit, Moog uses the ring for power, tip for positive and sleeve for negative, is that right? Sure its not hard to figure out I just need to crack open a manual. I’ll probably have to rewire the plug connections though.

Any more details on what you did voltor? Is it ok to lie the ribbon/tape flat on the board being used, with the guitar string above it?

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The S-VHS tape wears out…duct tape never does. I used a rubber washer on each end keeping the string off the S-VHS tape…I still have one S-VHS cassette, btw…you pay Priority Flat Rate shipping to my PayPal, and it’s all yours. :wink: As for your connections, yeah, that’s good. You can also use a 50k Ohm linear pot for fine tune if you don’t want to use the whole spectrum of the ribbon. I actually had the S-VHS tape above the string, with a strip of duct tape on the back of it for aesthetics, as well as function. If the string is on top, no duct tape should be used