606 fun

[Stewart Pye]

At 02:29 AM 15/07/99 -0400, WeAreAs1 at aol.com wrote:
>Hello Stewart,

>Could you take a moment to describe your MIDI to trigger unit in more
detail? 
> How many trigger outputs does it have?  What sort of microcontroller?  What 
>is the range and resolution of velocity sensitivity?  

8 trigger outputs
PIC 16F84 microcontroller
6 Bit R2R discrete DAC output:
I stripped the LSB of the velocity byte to get 64 steps rather than 128. I
used a dicrete dac because it is cheap and easy and does the job well. If I
could buy a voltage output DAC locally and for a good price, I would have
used that. At present it has 2 puhbuttons and a 7seg LED display which is
used to select midi channel and key range. One key selects wether you edit
midi channel or key range, the other key increments the value. I think when
I do the PCB I'll do it for two 7seg LED's so regular people don't have to
know that F = 15 :)  ( It's a rats nest at the moment)

>By what means are you 
>achieving analog velocity sensitivity?  

Say It gets a midi note on that triggers ch1....
The velocity byte is sent to the DAC...
The analog mux (4051) is set to ch1 and enabled...
Each output of the mux goes to a sample/hold buffer.(just an op amp buffer
with a 0.1uFcap to gnd)
After about 5ms the output is brought low again.
  
>Is the unit working to your 
>satisfaction?  

Still a bit of debugging and fine tuning to do. Maybe this week!

>With regard to the 606, you suggest connecting a variable trigger to
whatever 
>instrument trigger in and leaving the accent disconnected.   When triggering 
>from a variable amplitude pulse, what is the usable range of trigger 
>amplitude that will reliably work with a typical 606 instrument input?  (for 
>instance, the snare input)

Haven't tried this, but on the DR110 it responds to a low, <2V maybe, pulse
up to above 5V then reaches a point where it will distort. IIRC (guessing
here)
 
If you want really good dynamic range you might need a vca after the drum
synth and always give the drum oscillator a nice high pulse. 

Regards,
Stewart