[sdiy] VCO reset time

[jhaible at debitel.net]

> 1)  What is a good ramp reset time ? 

5ns ?

Discharging a 1nF cap @ 5V with 1A; doesn't seem _that_ extraordinary.

1ns ?

5A seems a lot, and making the cap 200pF might cause other problems ...

But there are other things to consider:

(a) comparator response time. How fast from the tiniest bit of overdrive
to trigger the discharge action.

(b) leakage, or the "other end" of the frequency range. Do you "only"
want an extremely fast-reset audio VCO, or should it also work down
to 1 cycle/minute without waveform distortion as a LFO?

(c) compatibility. I don't think 1A discharge is that difficult, but
if you also have a fast and sensitive trigger circuit (see (a)),
what will a second VCO of the same kind do when the first one triggers?
(soft sync by EMI ?)

JH.




> Hiya kids
> 
> I'm playing with a new experimental VCO core.  I will NOT tell you what
> it is...
> however if it has merit I'm going to publish it in EDN Design Ideas (it
> is cool enough
> that it will probably get accepted - after all they publish some really
> marginal stuff sometimes...)
> Of course if someone offers me the same $100 I'll probably talk :^P
> (you will need a lot
> more to get me NOT to talk)
> 
> Several questions...
> 
> 1)  What is a good ramp reset time ?   How fast have you seen ramp reset
> be ?
> 
> 2) How many octaves do you expect (in tune) without resorting to HF
> compensation
> 
> (I have not tried hf comp yet...)
> 
> Because I don't want to prejudice anyone... I won't say how fast my ramp
> reset is... but
> I will after I get some opinions.  I don't know how many octaves I'm
> getting ... I need to
> instrument differently. I'm thinking I mught do a lissajous figure and a
> binard divider to tell
> how well I'm doubling octaves
> 
> Gentlemen (and ladies ;^) start your opinions !!!
> 
> H^) harry
> 
> 
> 




-------------------------------------------------
debitel.net Webmail