MOTM

This circuit converts the bipolar output of the MOTM 320 into a
single-sided signal to be used with pedal inputs.  It in no way modifies
the MOTM 320.  Consider it a separate module.  Thanks to Larry for his
input.

It consists of two op-amps.  The first op-amp is an inverting summing
amplifier.  The second op-amp is an inverter.  In ascii, it looks like this:



         +15V
           |
           /         49.9K
      300K \   +----/\/\----+            100K
           /   |            |        +---/\/\-----+
    100K   |   |      |\    |        |            |
IN--/\/\---+---+---(-)| \   |  100K  |     |\     |
                      |  >--+--/\/\--+--(-)| \    |
               +---(+)| /                  |  >---+---- OUT
               |      |/            +---(+)| /
               =                    |      |/
                                    =


Each op-amp is half an LT1013.  The first op-amp is run off of the -15/+15V
supply.  The second op-amp is run single-sided to prevent it from
outputting a negative voltage.  Bypass caps are not shown.

The LT1013 was chosen primarily for two reasons:  1) it's DC accuracy  2)
it will run single-sided with inputs up to 300mV below ground.  An OP213
has very similar characteristics.

All resistors are 1% 1/4W.  Without any input, it's output is 2.50V.

I built this thing and it works.

Monkey Tested.
Monkey Approved.



DISCLAIMER:  I am not EE.  I do not speak for Synthesis Technology,
             or anyone else, nor should I. Any possible information
             is provided purely for entertainment purposes. I take
             no responsibility for the veracity of any claims.  If
             attempting to use this circuit results in you
             destroying your modular, that's your problem.