[sdiy] They aren't sawtooths, they're ramps

[cheater cheater]

They aren't sawtooths, they're ramps... from Dimension TL07-X!!!

On 05/11/2009, David G. Dixon <dixon at interchange.ubc.ca> wrote:
>> At 11:29 PM 11/4/2009, David G. Dixon wrote:
>> >This reminds me, I have now grafted the 2164 Expo onto the Thomas Henry
>> >triangle-core VCO-1, and laid out a very tight PCB (2.1" x 5.5") with
>> very
>> >low parts count which also includes Ray Wilson's sine shaper (to use up
>> the
>> >extra 13700) and a variable sync.  Simulations suggest that the tracking
>> >should be almost perfect, as it should be much easier to obtain excellent
>> >tracking with the VCO-1 then with JFET-switched saw-cores.
>>
>> How fast is that switching in your simulation?  My best Tri's and Saw's
>> aren't all that different regarding tracking. They both switch in ~200 ns.
>
>
> According to the simulation, switching from the prevailing level (+/-5V) to
> ground takes about 50ns.  Then, it takes about 200ns to settle to the low
> trigger level, and about 800ns to settle to the high trigger level.
> However, the triangle has already reversed direction once the main part of
> the switching transient occurs.  Therefore, I'd say that the switching takes
> less than 100ns.  This is based on a discrete schmitt trigger made from two
> 2N3904s, with a 47pF speedup cap (see Scott Stites's website for the VCO-1
> schematic).
>
> Also according to the simulation, this circuit will need only a very small
> amount of HF trim to track well up to 16kHz (and presumably beyond), with
> TL07x everywhere.
>
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