[sdiy] TB303 Slide

Gordon JC Pearce gordonjcp at gjcp.net
Sat May 26 06:29:07 CEST 2012


On 26/05/12 01:23, Tim Stinchcombe wrote:
>> Does the R2R DAC in the TB 303 feeding the glide capacitor directly
>> actually achieve constant glide time regardless of the voltage span
>> between notes. (ie: glide time from 1V to 1.83V is the same
>> as from 1V
>> to 2V?)
>
> Yes. The output resistance of the DAC is always 100k, regardless of the
> voltage, and so the time constant with the 220n (C35) is 22ms - thus after
> about 60ms the slide is complete, no matter how large or small the voltage
> change was.

Yup.  Counter-intuitive as it sounds, the time taken for the slide 
doesn't change with the voltage swing.

If it did, RC filters would tune differently depending on the level of 
the input signal.

-- 
Gordonjcp MM0YEQ



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