i did moe's manual pushbutton gate mod and it works great.
http://motm.retrosynth.com/markus_stuff/motm800 mods
mark
At 06:55 PM 3/12/02 -0500, you wrote:
>For quite some time I've been contemplating a couple of enhancements to
>the 800 ADSR generator. The obvious "wants" are a manual gate switch (to
>audition that portion of a patch), either a "gate on" LED or a gate output
>LED (that tracks voltage level via intensity), and an adjustable gate delay.
>
>The gate LED has already been done
>(http://www.hotrodmotm.com/800_mods.htm) and a manual gate switch is
>pretty much cake, but the delay option is a little more involved. Am
>looking for opinions on the viability of this idea: Add the activity LED
>like Moe did, add a manual gate switch as has been suggested by many, and
>turn the SUSTAIN pot into a dual-use mode: SUSTAIN/DELAY. I envision that
>a multifunction piggyback board be added to the 800. The manual gate
>switch (an NKK switch to match other MOTM modules) is used to trigger a
>gate on-demand. But this added NKK switch would have a center-off, and
>momentary On/On capability. When the NKK switch is lifted, a manual gate
>is created and the 800 module works as if a gate-in has been
>received. Let go of the added NKK switch and all is normal (gate goes
>away). But, press down on the added NKK switch and you have selected the
>"delay-time-set mode". Using the existing SUSTAIN pot, adjust for the
>desired DELAY time wanted (1 millisecond to 10 seconds, log
>curve). Release the added NKK switch and the module works as normal
>except that the added piggyback circuit "remembers" the selected delay
>time and delays each incoming gate by the user-selected amount. (Of
>course the SUSTAIN pot will have to be adjusted back to where it was
>before you adjusted the delay time.) By again lifting the added NKK
>switch, one can audition the delay time just added.
>
>Getting this to work is not difficult. But would this be a workable user
>interface? (Yes, the SUSTAIN pot is linear... the conversion to a
>log-taper for time-delay adjustments would be handled by circuits on the
>piggyback board using a PIC processor, a couple of opamps, and some
>passives. And yes, just like a dedicated pot, the piggyback circuit would
>remember delay settings even after the synth is powered down. This
>circuit is designed, but not yet prototyped.)
>
>Lastly, I would sacrifice the -ENV output in favor of a voltage control
>input for the delay time. That way, delay times could be made to vary by
>note, random event, or anything else one could dream up. This
>modification would certainly require some hacks to the existing 800
>module, but should be minimal in severity and number. The changes would
>be reversible. I would suggest that a pair of MTA-156 connectors be added
>to the piggyback board and use a short (3") MTA-to-MTA cable to supply
>power to the 800 board to preserve use of the existing cable.
>
>In conclusion, one would end up with an 800 that has a manual gate switch,
>gate activity LED, an adjustable gate-delay over a wide range of times,
>and a gate-delay voltage-controlled input. That, while adding only 2
>small holes in the front panel of the MOTM 800 (LED and NKK switch).
>
>Comments?
>
>Cheers!
>Tom Farrand
>
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