[sdiy] Blackmer cell

[James Patchell]

A few years back, I experimented with this type of VCA (using a THAT140 for 
the transistors)...and for some odd reason, which I can't remember, I 
decided not to use it for the application I was doing.  It is a fairly 
simple VCA to build.  You will find a complete circuit for it in the LM194 
data sheet.  This is what I built up, but like I said, I used the THAT140 
instead of the LM194/2n3810 transistor pairs shown there.

At 02:35 AM 12/6/2005 -0500, Aaron Lanterman wrote:

>On Mon, 5 Dec 2005, JH. wrote:
>
>>It's a Blackmer cell. No offset to speak of (compared to OTAs),
>>but needs a servo configuration which probably limits its speed.
>
>I hadn't encountered the term "Blackmer cell" previously.
>
>In playing with VCA designs, is it worth experimenting with building some 
>discrete Blackmer cells?
>
>See http://www.edn.com/article/CA236413.html, Figure 3...
>
>http://www.edn.com/contents/images/236413.pdf
>
>- Aaron
>
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>
>Dr. Aaron Lanterman, Asst. Prof.       Voice:  404-385-2548
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         -Jim
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