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On 20-Mar-09, at 2:19 PM, Scott Juskiw wrote:
> I haven't built my scanner/vibrato yet, but I have worked out a list
> of elements that the panel will require. Anybody want to take this on
> and try to design something?
>
> Required:
>
> 1. Audio In/Out: 2 jacks (IN and OUT)
> 2. Interpolating Scanner Controls: 9 jacks (IN), 9 pots (LEVEL), 9
> LEDs
> 3. LFO Rate Control: 1 jack (RATE CV IN), 2 pots (RATE, RATE CV)
> 4. LFO Depth Control: 1 jack (DEPTH CV IN), 2 pots (DEPTH, DEPTH CV)
> 5. Scan Control: 1 jack (SCAN CV IN), 2 pots (MANUAL, SCAN CV)
> 6. Lag Control: 1 switch
> 7. Chorus/Vibrato control: 1 switch (see ∗note 1)
> 8. Function control: 9 pin 4 pole rotary switch
>
> Optional:
>
> 1. Input attenuator (for Vibrato/Chorus): 1 pot
> 2. Lowpass filter (for Vibrato/Chorus): 1 pot
> 3. Celeste control (for Vibrato/Chorus): 1 switch (see ∗note 2)
>
> ∗Note 1
> There are several possibilities for the Chorus/Vibrato control:
> a. 1 switch (as shown in the schematics)
> b. 1 pot (as Dave Brown did)
> c. 1 switch and 1 pot (as JH did)
>
> ∗Note 2
> Here's what JH had to say about the Celeste switch:
>
> "Celeste is an option for which no on-board connector is provided,
> namely removing the termination resistor of the delay line, R104, from
> the circuit and thus causing reflections of the delayed signal back
> towards the input of the delay line. If you want to implement this,
> lift one side of R104 from the PCB, and re-connect it via a switch."
>
> Here's what Dave Brown had to say about the Celeste switch:
>
> "The Celeste switch adds a 0.01 uF and 2K resistor in series with R104
> to mis-terminate the delay line causing reflections. I selected these
> values empirically."
>
> Sounds like there is some room for experimenting with the Celeste
> option. It's possible that a pot could be used to control the level of
> mis-termination, but someone would need to verify whether or not this
> is worthy of taking up panel space. Having a Celeste switch is
> probably worthwhile.
>