[sdiy] Other dedicated V-to-freq chips

[Magnus Danielson]

From: Aaron Lanterman <lanterma at ece.gatech.edu>
Subject: [sdiy] Other dedicated V-to-freq chips
Date: Sun, 20 Apr 2008 21:50:08 -0400
Message-ID: <BC5F194E-A121-4F0D-A630-BDB5D0D7DB4D at ece.gatech.edu>

> Ian's recent experiences with the LM331 made me wonder if some other dedicated V-to-freq chips were worthy of exploration?
> 
> I have datasheets for the following on my http://users.ece.gatech.edu/~lanterma/sdiy/datasheetspage:
> 
> � Analog Devices AD537 ($13.74/1 Digi-Key) (may be overkill for synth work)
> � Analog Devices AD654
> � Analog Devices ADVCF32
> � National Semiconductor LM231/LM331 ($6.38/1 LM231, $2.8/1 LM331 Digi-Key)
> � Fairchild KA331
> � Exar XR2206 ($3.59/1 Jameco)
> � Exar XR2209, Radio Shack Ap Note
> � Exar XR4151 (used in the Rhodes Chroma!) ($1.29/1 Jameco)
> � Microchip TC9400/9401/9402 ($6.881/1 TC9400, $7.01/60 TC9401, $3.25/1 TC9402 Digi-Key)
> 
> The XR4151 is the only I know of to turn up in a commercial synth.
> 
> Some of the above chips appear in posts in the SDIY archives, but the reports tend not to be highly enthusiastic - but most of them have probably not been subject to the Fritz treatment. I think Ian could make an in-tune-for-10-octaves zero-heat-drift VCO out of a rubber band, a box of legos, and a caffinated ferret.

Hold the ferret, strong on the mayo please!

I just recalled that the Elka Synthex uses a pair of high frequency V-Fs which
is divided down in a organ style. The waveshaping is done using counter tricks
while modulation is done on the HF generators. The benefit is low need to trim.
Too lazy to dig up the schematics, but I could do that if needed.

Cheers,
Magnus