On 11 Feb 2007, at 23:44, Scott Juskiw wrote:
>> I've finished my MOTM-101 noise/s&h, and the clock range seems a bit
>> too low. According to the specs it should be 0.1 - 20 Hz typical, but
>> I measure 0.4 .. 13.7 Hz. Which I think is a bit off, to be within
>> the 'typical' range. :-)
>
> It's probably the pot (VR2) that is the problem. Most pots are only
> good to within 20%. There's not much you can do to increase the pot's
> maximum resistance (which affects the lowest frequency of the
> internal clock), but you can change R23 to compensate. You can also
> increase the highest frequency by lowering R22.
The pot is 95 k, so it is not too far off. I've just calculated the
frequency range that I should get with the component values that are
in the kit, and my measured range is actually close to what I've
computed. (I did not see the trick with the diode across pin 2 and 7
before, nice!)
On the other hand, I just checked the latest MOTM catalog and in
there it says 0.2 .. 25 Hz. So that is yet another set of values.
Which is right???
In the end, the musical effect is what counts. So the real question
is, is 0.4 .. 13.7 Hz okay for that, or would it be a good idea to
tweak the values to some other range?
Ben