[sdiy] More VCO fun

[Oren Leavitt]

ASSI wrote:
> On Tuesday 08 December 2009, David G. Dixon wrote:
> 
>>I just simulated your solution, and it is WAY BETTER!  Resetting is
>>occurring in just about exactly one microsecond.  My feeble,
>> inappropriate JFET is now truly happy!  And, the kludge will be
>> incredibly easy on my existing layout, which is a bonus.
> 
> 
> I think R22 in Oren's schematic should be connected to GND, not +15V.  
> The way it is wired now the diode doesn't match up with his 
> description.  You can shed another resistor by using my original 
> suggestion:
> 
> JFET Gate o--------+-----/\/\/\-----o +15V
>                    |
> Comp Out  o--------+-----|>|--------o GND
> 
> You can use a normal low-Vf diode if you don't have a Schottky  ...and 
> if you keep the low-cutoff transistor you might still want to connect 
> the emitter of the output stage to something a little bit higher than 
> -15V.  A Zener between pin 3 and 6 should do that, the current is 
> already limited by the resistor going to +15V.
> 
> 
> 
> Achim.

Hi Achim,

Thanks for the info - I'll have try that the next time I have 
oscillators on the bench. I do have some 1N5817 Schottky diodes that are 
"looking for something to do".

- Oren