[sdiy] LM394 vs. MAT02 vs. ?

[Scott Bernardi]

I've used these npn-pnp expo converters in non critical applications 
like LFO's and filters, for driving OTA's.  They work pretty well. It's 
pretty neat to get a very usable wide range LFO out of two transistors, 
an opamp, an OTA, a cap and a few resistors.
René Schmitz wrote:

> Hi Scott and all,
>
> Scott Stites wrote:
>
>> Rene's VCO4069 uses an NPN/PNP pair.  But, maybe was inspired by the 
>> ARP design? =0)  In any event, it does deliver an expo response.  
>
>
> The Minimoog Filter used a similar convertor as well. Sure it has been 
> inspired by ARP and Moog. I had my doubts about the octave purity of 
> this circuit as well, and I have to say that I was pleasantly 
> surprised, especially if you consider the means involved. The question 
> is what you compare it against, if you take a 3046, then the much 
> lower Rbe of the discreet transistors is a plus for the NPN/PNP 
> circuit, and if you look into the MAT02 direction, then surely they 
> are out of competition.
> The big question is what you find acceptable, and thats one thing that 
> everyone has to decide for oneself.
>
> Cheers,
>  René
>