[sdiy] More on the AN299 VCO

[Ian Fritz]

At 01:26 PM 4/30/2008, flightofharmony at comcast.net wrote:
>Which is why it didn't work well the first time around!

So ... you were heating the reset transistors?


>This time, I assumed that Q6 in the App Note would correspond to Q5 in the 
>array. So far, it's been pretty stable: after one hour running in open air 
>it has only shifted by ~1.5Hz. I'm assuming proper thermal insulation in a 
>closed box would cure that.

I've always thought that thermally isolating and insulating the array might 
be something worth trying.  This would lower the power consumption, and get 
rid of the problem some people have had of the heat affecting other components.

The only heated VCOs I have are a pair of SSM chips.  They do drift for 
quite a while before the temperature stabilizes.  The servo adds some noise 
to the output, which is another issue people don't talk about.


>The remaining problem is the max. frequency is around 1950 Hz, then it 
>latches until the CV is lowered. I had this problem the first time as 
>well, any ideas? BTW - I'm using a TL082.

Hmmm ... not really.  :-)

It's ramping up and not resetting?

   Ian