Archive of the former Yahoo!Groups mailing list: 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.