[sdiy] 4069 VCO linearity SUCCESS

[René Schmitz]

Hi Scott and all!

>>>I'd recommend going back to your initial setup, with the emitters 
>>>going to the -input, base to out and +input grounded. The emitters 
>>>will be at GND due to the feedback. All you need to make it work 
>>>right is to add an inverting stage at the input.
>>
>>If I do that, I will have reverse biased NPNs...
>
>NO I WOULDN'T.  Jeez.  I need to try this, I have two
>opamps in the circuit anyway.  I *really* want to get
>rid of that resistor.

I think that it'll be working over the full range (i.e. up to ~50kHz). 

Btw, I now convinced myself that the cap sees a linear rising voltage, 
by using my scope in differential mode, monitoring the voltage over the 
cap. Interestingly the spike is also gone then. 

>You're right, René.  I have no idea what I was thinking.
>I have to stop getting so involved with this stuff that
>I forget to eat.  I'm a diabetic and I can start to
>'lose it' when I don't eat on time.  Well, it least
>this is *that* much fun!

Been there. Sometimes one gets carried away so far that one 
simply doesn't notice that one is totally tired or hungry. 

Cheers,
 René




-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159