DB-800 Daughterboard for MOTM-800 User Guide

The DB-800 is a daughterboard for the MOTM-800 EG. The DB-800 adds a comparator to the GATE input and a clipper to prevent the EG output from rising above +5 volts. The MOTM-800 requires a relatively fast rising signal at the GATE input to generate an envelope. Slow rising signals, like the SINE output from an LFO, will not normally trigger the MOTM-800. The comparator squares up any signal at the GATE input so that any voltage rising above +1.4 volts will trigger the EG. Two optional LED drivers are also provided, one for the GATE input and another for the EG output.
A comparator with hysteresis is built around U1. R1 and R2 set the upper trip point at approximately +1.4 volts. When the signal at the GATE input rises above the upper trip point, the output from U1 rises very quickly from 0 to +15 volts. The output from U1 stays at +15 volts until the signal at the GATE input goes below the lower trip point (approximately +1.2) volts. U1 then drops very quickly from +15 volts to 0 volts and stays there until the signal at the GATE input rises above the upper trip point again. This comparator circuit is placed between the GATE jack on the MOTM-800 panel and the GATE input pads on the MOTM-800 motherboard to generate a fast rising GATE from any input signal. U2b is a simple LED driver that turns on the GATE LED whenever the output from U1 goes high.



A comparator with hysteresis is built around U1. R1 and R2 set the upper trip point at approximately +1.4 volts. When the signal at the GATE input rises above the upper trip point, the output from U1 rises very quickly from 0 to +15 volts. The output from U1 stays at +15 volts until the signal at the GATE input goes below the lower trip point (approximately +1.2) volts. U1 then drops very quickly from +15 volts to 0 volts and stays there until the signal at the GATE input rises above the upper trip point again. This comparator circuit is placed between the GATE jack on the MOTM-800 panel and the GATE input pads on the MOTM-800 motherboard to generate a fast rising GATE from any input signal. U2b is a simple LED driver that turns on the GATE LED whenever the output from U1 goes high.
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