DIY Voltage Control projects for the Voyager, LP and foogers

[Portamental]

I knew it would get there eventually. Now I am in the thick of it, for a little while anyway. I have many many simple DIY electronics projects in mind. By the time I complete one, I get three more ideas.

All require only very basic parts (resistors, jacks, switches, a few caps, diodes or opamps here and there). I purposely avoid any complex or hard to find IC's. All are simple enough to be hard wired, though I will probably design and etch a few PCB's here and there.

Right now, I have a working CV expander on the breadboard. It's a simple voltage amplifier designed to amplify low level CV's (under 2 volts). Amplifier gain is 5, it has both regular and inverted output. It's only missing a few parts to clip voltage (to make sure they don't go over 6 or 7 volts) and a small pcb (optional). While it can be used right away for general purposes, I have something in mind for it that will be revealed in due time, after it has met my goals.

All are sound and safe (I know they are), although I don't make a public claim about it, and you building them and/or using them is your own responsability. They are suitable to people with only very basic electronics skills, like how to use a soldering iron and read a schematic.

One drawback, so to speak, is some of them will require an external power source, most likely the typical -15v +15 power supply used with many modulars, some other may require (or could be adapted to) self-contained power, such as one or two 9 volts batteries when negative voltage is involved. There would be other ways to power them, but this would require more parts and IC's, which is against my design criterias. I am always shooting for the simplest solution and low parts count.

If there's enough interest, I'll post articles about them, and if a little bit more interest, accompany them with pictures, schematics and PCB drawings.

There are two reasons for all this. First is to live by the motto if this Forum (Share Ideas and Pass the word), which is a philosophy I have always lived by in most anything I do. Second, to built really cool gadgets with an immediate and useful purpose, and that you would wait half a lifetime if you were to depend on companies making them. All that at super low cost.

So let me know what you think.

[Just Me]

I'm listening....

[LivePsy]

Hi Portamental,

Your posts are great reading I am also interested in building modular circuits. Unique modules for specific tasks rather than a whole wall of VCOs, VCFs etc. I think the Voyager with midi can be the centre piece, the VX expander providing its outputs. And a small modular system to go further with controls and audio processing.

Don't shoot me, but the Foogers would be better presented as modules - the MF-101 LPF for example makes more sense as a classic moog filter module, envelope follower module and some summing circuits. Once it is split into those modules, it opens the door wide open to experiments. The foogers do offer more than expected flexibility with the jacks at the back, but separate modules just seem simpler. The Foogers are certainly popular with Voyager owners, but I think a modular interface like the VX and CP provide makes more sense.

My view is that the first step in adding modules, particularly if you quite sensibly don't know where it is all going, is a case and power supply and method of adding modules to build a front panel. I know that usually gets left until later, or left to the reader to devise because apparently its a lot of fun (not). But IMO once the framework is in place, the ability to add modules whenever you have the inspiration or need flows easily. A mad collection of modules, some with battery, some with wall-wart PSUs, no uniform method of interconnecting and all wildly differing signal levels is most likely going to fail. For me, a collection of Foogers is a bit similar and won't be as productive as a modular interface.

So Portamental, your ideas are great and I really welcome them. But I do think that a framework comes first. I've been thinking that through in the last few weeks but haven't found the right one yet.

B

[Sidewind]

I like this idea a lot! I have been looking to build some DIY modules to augment my modular/Voyager/MF setup. Most things I found were not designed for a newbie in electronics building (me).

As far as power and cases go, I think that should be left for the user to decide. Otherwise, you will never please everyone. Besides, the real "meat and potatoes" so to speak are the modules/circuits themselves.

So I eagerly await the details - soldering iron in hand....

Michael...

[Portamental]

Livepsy : thanks for you comments, they are most welcome.

No I won't shoot you down, but we can differ in opinions. I like to experiment with electronics and build things. I plunge right in and try all sort of things. Once I get to the final stages of the building, that's when I agonize over the most silly decisions. Should I make this box 11 inch and half wide or 11 inch and a quarter? Should i put this row of jacks one inch from the top or two inches? What if i want to add more stuff later on? I never ends. As a result, the 7 amp power supply I use for musical instrument is still bare, a bunch of wires coming out, a few of them still have twisted ends covered with electrical tape (I must say I am out of shrinking tubing) and the bare unit is still attached to the bottom legs of my rack with electrical tape. However it's been feeding 8 to 10 musical instruments (replacing that many wallwarts) simultaneously for 3 months now. Similarly, when breadboarding, i find it faster to reach in my scrap box, grab two batteries holders for instant + and - voltages than even walk into the next room and bring a power supply that i have to connect into the wall, and that may not have the proper voltage output anyway. etc etc. That's what works for me.

There's no avoiding the power supply issue, so I guess that'll be one of the first articles.


Sidewind :

Right on. Real working electronics for beginners. I myself ain't the more knowledgeable electronics person. I seems to me that some of the electrical theory took a long time sinking through my thick skull. Many parts are still settling in. But what I know I try to make the best of. And I get results. I like the KISS principle, both in hobbies and personal relationships

It's worth mentioning that all things electronics mystify a lot of people, and these projects written in a tutorial fashion will go a long way for people to understand what's going on at the electron level. It's a very important aspect of the whole issue, and i think they are going to be worthy reading even for the non-builders.

So people : ask questions and throw in your ideas. It's the best way to get some work done.

[LivePsy]

Actually Portamental, I felt bad about shooting you down. And my obsessing over a uniform format for the modules power, casing and connections is based on building amatuer modulars in the 70s. A mate of mine really did build a minimoog clone from the circuits. My attempts were more like some analog modules and an EMS in a suitcase. For both me and my mate the results were fantastic to us back then, but not having the proper manufacturing techniques showed in the appearance and sounds. You need clean power, good shielding in some parts, a reliable and noise free cabling method, the list goes on. And just aesthestically, a row of pots or sockets all uneven and you tried so hard to get them right ... aaargghh!

So, years later I bought myself a Voyager. Both as a tribute to a great object of desire from my teenage years, and because it is properly manufactured. Solid, great sounding, semi modular, modern options better than the original minimoog. Oh, and all the knobs and sockets perfectly aligned. My humble wish is that whatever I add on to the voyager is similar in build quality.

So all up, I'm in! I'll just be behind you front runners, sweating the small stuff

B

[sunny pedaal]

can the voltage amplifier be set to other values then factor5 too, can it be manually adjusted ?
i've looking a long time for a thing like that, if only to be able to adapt the moogs to other volt/oct synth's . after all i need 1volt/oct and not 0,9 something like with the voyager/ multimoog etc.
so already for that one: stop the talking , lets go walking
otherwise said, : i'm in

[LivePsy]

The Moogs at less than 1V/Oct is an advantage in disguise. It allows you to match differently calibrated oscillators with just an attenuator such as the VX and CP modules provide. It would be far worse to have an oscillator which was 1.1V/Oct, because you could not get it to track. Better to have an oscillator at 0.9V/Oct so you can adjust the frequency CV to match.

So erring on the low side of 1V/Oct is quite sensible.

B

[sunny pedaal]

think my old minimoog is 1.1
the multimoogs aftertouch however is out of reach for the other analogs i have as it gives out 0.9 volt, whereas rolands certainly need 1 volt/oct.
so it's a shortcoming , i think, not to confirm to the 1 volt/octave standart.
hope the invention you mde helps in these cases ?

[LivePsy]

Yes you're quite right sunny. Other gear to Moog is easy because of the less then 1v setup. But Moog to other gear isn't easy. You would need an amplifying op amp circuit. If you happen to have a CP module, your CV could go to a multi then two connections from the multi go to the four input mixer. This doubles the voltage, then you can scale it back with the master level and maybe add offset. The CP box is a marvellous collection of tools in a small form factor.

I'm a little concerned that the most obvious DIY projects will be replacements for the VX and CP modules. While they are not inexpensive, they are extremely well made and Moog should be proud of them. I recently mounted one of each into a Moog rack mount kit and once again, the quality is superb. I'd hope that DIY projects discussed here are focussed on extra features and don't just try to save money instead of purchasing the excellent VX and CP products.

The things I am interested in: step sequencer, knobs to CV (just panel mounted pot versions of the expression pedal), audio waveshaping.

Cheers,
B

[jon_kull]

I'd hope that DIY projects discussed here are focussed on extra features and don't just try to save money instead of purchasing the excellent VX and CP products.

I don't. I personally would love to see a DIY solution for the VX351 regardless of how well made the VX is especially if I could customize it. I have an Old School. I'd like extra velocity, pressure, saw and square LFO outs in place of the 4 useless touchpad outputs. I'd also move the accessory port jack off the front panel and try to squeeze in an extra row of attenuators which should be doable with smaller pots and knobs.

[Portamental]

can the voltage amplifier be set to other values then factor5 too, can it be manually adjusted ?

Well the circuit could amplify more than 5, 10, easy, and made variable too. But that depends on the source supply too, then again, by design it will be limited to -8 to 8v. Before the final design of the amplifier, there's something I am working on derived from this (it's a little surprise for later) and it may influence the amplifier itself. That's a project for down the road.

-----------

Now that I have committed to writing articles and projects, the first three are already written but I realize the packaging is more work than anticipated. I want them properly written, well formatted and fully documented with pictures. One of them is accompanied with a computer program too. Need a least one visit to electronics warehouse, thursday I think.

Hopefully, I will post the first two projects by this week-end.

[Portamental]

Regarding the 1V/oct discussion .. that's the standard specification that is the norm right now. For those vintage that differ slightly, that can be arranged with a CP-251 (to some) extent but a DIY circuit makes a lot of sense, exactly in the spirit of these articles. Basically a 1 gain amplifier, adjustable to -+25 % with a trim pot. Once calibrated (by ear will be fine), it will keep pitch and operate worry free. Just a few $ worth of parts.

This is not about saving money or replacing the ready made products that we all love. But it's about fun and complementing them, sometimes with something different, sometimes with the similar. In my particular case (an OS for now) , i need a second CP-251 much sooner than a vx-351. Actually I just need the cv-outs from the OS and there's a DB-25 waiting for that, so one of the projects will be about a CP style expansion to blend in and accommodate the forthcoming circuits and Voyagers CV outs.

[Portamental]

I can't believe it's been three months since this. I was a bit idle a the time but I was soon hit with an unexpected work load. Things are starting to ease, and projects are adding up. It takes more time writing about them than it takes building and testing them most of the time. And if there's only one thing in the world better than building DIY projects for the OS, that would be playing music with it. Hopefully, i'll be able to post something soon.

In the meantime, here's an ordered list of exactly 25 things about the Voyager OS. I like (and have used) 21 of them

Ground
Floating 0
Floating 0 (not sure)
Velocity
KB gate
Mod 2
Mod Wheel
Mod Bus 2
Volume Env
LFO square
LFO triangle
5v supply
-15v supply
Floating 0
Floating 0
Pitch
Pressure
Mod 1
Pitch wheel
Mod Bus 1
Filter Env
SH smooth
SH step
Noise
15v supply

[RL]