[sdiy] Saw core JFET mystery

[Aaron Lanterman]

On Mar 1, 2010, at 8:11 PM, David G. Dixon wrote:

>> Yep, that looks pretty much like mine, albeit with different component
>> values...
> 
> except for that transistor on the end of the comparator.  What's up with
> that, Magnus?

Danger Will Robinson!

I had a student build this a couple of years ago:

http://home.swipnet.se/cfmd/synths/friends/stopp/asm1vco-1.1.pdf

and it turned into an absolute nightmare because of the confusion that transistor caused. It worked muh better once we knew to not include an actual transistor there.

That transistor is *part of the LM311* - it's trying to illustrate the open collector output of the 311. 

Repeat, repeat, *don't* put a transistor in that spot - just hook the output of the 311 to the node connected to the collector of the phantom transistor.

- Aaron