[sdiy] Discrete OTA

[Rutger Vlek]

Hi guys,

Haha, thanks for the enthusiasm! It is very tempting to reveal what I have been working on, but I'm a little hesitant at the moment. As I explained to you I'm looking to move away from academia. I just finished my PhD, but working under the enormous pressure in a high-tech lab environment has resulted in a severe burn-out. I'm slowly getting back on my feet again, but this is taking long. For the future, I'm looking for a different way to earn money. This is why I'm thinking about starting up a company. I absolutely love working on synth design (especially in the DIY community). Normally I would be all for "open source" and sharing the ideas that I have, but the intellectual property may now become relevant for my income. That's why I'd like to figure out some way of protecting the IP. Any thoughts on that? I see many companies currently doing the "open hardware" licensing thing.... Would that provide enough protection for designs, schematics and layouts to prevent someone else from slavishly copying and making money off my designs?

Ok, now the more interesting part..... I have something on my test bench that contains VCAs and a VCF design with discrete OTAs. I haven't tested the VCF yet, but the VCA performs pretty good. I don't want to make any strong claims at this point about it, since I'm not a skilled electrical engineer. Just a hobbyist with general scientific skills. My goals were roughly to develop a discrete OTA that can be made moderately cheap. I have not been aiming to beat high quality alternatives (2164, THAT-chips, etc), but was rather aiming for an alternative with a bit of character (think of the way the ca3080 saturates). There are several ways my prototype could be made available to others, and I'd like to hear about your preferences:

1) Because of the topology it will never be an exact drop-in replacement for any existing OTA, but I believe it is possible to fit a single discrete OTA on a tiny DIP8 daughterboard. For good temperature stability it probably needs potting too. If I had to estimate a price, it would probably be around 5 or 6 euro's, possibly a bit cheaper in larger quantities. Is this still feasible for the DIY community?

2) I could also turn the entire discrete OTA-based VCA into a tiny daughterboard, including lin/log option for the current source, etc.

3) I could turn the prototype into 'ready made' or DIY-kit Eurorack modules, VCA, VCF. I already have some other innovations for a VCF on the bench too, so that would be included.

What would you prefer?

Best,

Rutger

ps. Any experience with companies that do potting (with heat-conducting epoxy)? Or can this be done cleverly DIY, yet still for high quantities?







On 30 mrt 2014, at 22:22, Tom Wiltshire wrote:

> 
> On 30 Mar 2014, at 19:15, cheater00 . <cheater00 at gmail.com> wrote:
> 
>> Rutger,
>> 
>> On Sun, Mar 30, 2014 at 8:06 PM, Rutger Vlek <rutgervlek at gmail.com> wrote:
>>> Have recently been working on prototyping a new idea for a discrete OTA and obtained pretty good results!
>> 
>> ok, now you GOTTA tell us eeeeverything about it. I expect photos,
>> schematics, sound examples, Bode plots, and a dev board layout! :-)))
> 
> 
> Or start the company so we can buy one!
> 
> Tom
> 
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