[sdiy] asm2 vco problems

[Magnus Danielson]

>
> THANKS
>
> "
> I'd expect something like a few 100 kHz or so.
>  "
>
> do you mean a few 100 PF?

No, the expected frequency of the oscillation that I expect is there... I
suspect it just resets for a short while but not enought to empty it out
fully and then it is charged again and then resets partially. That what I
experienced and I know several others have experienced this too.

If the reset circuit did not do anything, I'd expect the capacitor to
integrate up to full power-voltage. I suspect it charges up to the limit
(as set by the three resistors with a transistor, as referenced to the 10
Vref voltage) the LM311 kiks the JFET which starts the discharge, but the
time-constant makes the LM311 give up too soon and thus it will start
again. It could of course lock to a fixed voltage. Try forcing a reset
through the reset circuit and see if the JFET does discharge the cap
fully. Then see what happends as you release the RESET. To maintain reset
state long enought, bypass the cap for this test.

Cheers,
Magnus