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Gnome Instrument Interface

Using the 2720-11 Envelope Follower


For those of you who like to avoid making your own circuit boards and tracking down the parts for your projects, we present an alternative. You will still need to install an external input jack, and this can be connected to the Gnome's noise circuit as shown in Craig's circuit or it can be connected directly to the Gnome's audio buss (Ts-2, lug 3) through a 2.2 mfd. electrolytic capacitor as shown in figure B.

Note that the positive lead of the capacitor will go to the audio buss, while the negative lead goes to the tip connection of the external input jack.

To provide the signal detection and triggering function, you can use the PAIA 2720-11 Envelope Follower module. The external signal source will be fed to both the 2720-11 and to the Gnome external input. The desired trigger (step or pulse) output of the 2720-11 is then patched to the external input of the Gnome (the black pin jack on the rear apron of the case).

Figure B
[Errata: The point labeled GNOME INPUT should be; GNOME OUTPUT]


Be sure to have a common ground between the Envelope Follower and the Gnome in order for the trigger signal to have effect.

As an extra bonus, the 2720-11 has an envelope control voltage output. The voltage at this jack is a DC voltage which varies from 0 to 7 volts and is directly proportional to the amplitude of the signal applied to the input of the 2720-11. The wiper probe of the Gnome can be inserted into this envelope output and you can sweep the frequency of the Gnome's VCO or VCF each time a signal is generated by your external source. This particular set up can yield a great variety of effects.


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Polyphony - Copyright: Polyphony Publishing Company

 

Polyphony - Oct 1976

Donated & scanned by: Vesa Lahteenmaki

Feature by Marvin Jones

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> Interfacing External Signals...

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