[sdiy] Best CA3280 projects?

[Rutger Vlek]

Yes, I tried making a discrete clone in Spice (mostly CA3080 and LM13700). Matching of the various transistors, and keeping the whole thing temperature stable is hard though. An interesting thing is that most IC OTAs required rather complex designs to overcome a relatively low current-gain per (internal) transistor. Modern discrete transistors have much better specs, so you can do with fewer of them. Matched transistor pairs also have become cheaper. I'm now in the process of prototyping a really simple discrete OTA core, which according to Spice should outperform an LM13700. Fingers crossed... If it works, I'll share it.

Rutger

On 30 jun 2012, at 13:55, Tom Bugs wrote:

> Makes me wonder...
> 
> Would it be possible to make a very compact sub-board discrete CA3280 clone?
> 
> Anyone done any work on such areas?
> 
> Best, Tom
> 
> On 30/06/2012 00:03, James Coplin wrote:
>> So, I'm cleaning up my work area and going through part drawers etc. and I
>> realize that my cache of 3280's I have on hand for repairs etc. is larger
>> than I will need for repair parts in the future.  I have a few 3280AE but
>> mostly 3280E chips.  What is folks favorite projects that I could use
>> these for?  I want it to be something that I would have to use 3280 rather
>> than an excuse to use the chips up.  In other words, I can make a good VCA
>> with the 2044 so making one with the 3280 isn't exactly a good use of the
>> chips (or is it?).  I await your flood of suggestions for use.
>> 
>> James R. Coplin
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