LM566CN VCO

Rene Schmitz uzs159 at uni-bonn.de
Wed Jul 1 22:40:26 CEST 1998


At 22:38 30.06.1998 GMT, you wrote:
>On Tue, 30 Jun 1998 22:44:11 +0200, Rene Schmitz <uzs159 at uni-bonn.de>
>wrote:
>
>>At 23:05 29.06.1998 GMT, you wrote:
>>>Well, the spec claims only 10 to 1 freq range.  That's only a little
>>>more than 3 octaves.  Unless someone knows of a way to extend this,
>>>that seems kind of lame for music.
>>It seems that the 566 can be current controlled as well, and in this
>>case the sweep range is more like 1 to 100, I have a schematic for a
>>BBD phaser at hand where this is used. They hold the voltage input at
>>some fixed level, and inject the current at pin 6. Hm, sounds as if one
>>could add a simple expo converter and have linear and exponential FM.
>
>I went back to my National book and I see no mention of a change in
>it's useful linear range for current control.  Where did you come by
>the spec of 1 to 100?  If it is true, it would make an easy to build
>VCO, but only if it is linear over that range.  Is it possible that it
>will work over that range, but that it might not be linear enough for
>music?  If I had one of these, I'd try it now, but I'd rather not buy
>any unless I know I can make a VCO that's at least as linear over a
>range equivalent to the FatMan's.

The range is not in the spec, I've looked there myself, and it says only 1 to 10
with voltage control, but the pin 6 is actually a current input.
In the BBD phaser where I saw this, the VCO had a frequency  range of 10kHz
to 800kHz
not 1 to 100 but close.
Maybe I've some 566s arround here and give it a try...

-Rene
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