Grumpenspiel MIDI Circuit Reference

Overview

This page is a reference for MIDI IN, OUT, and THRU circuits. Additionally, it includes Power Thru compatibility.

PINOUT

MIDI 5-pin DIN front
MIDI 5-pin DIN back
PinMIDI OUTMIDI INPower Thru
1 n/c n/c GND
2 GND n/c
3 n/c n/c 5V DC
4 VCC through Ra 220 resistor Opto-Isolator pin 2 through Rb 220 resistor
5 UART signal Opto-Isolator pin 3

MIDI OUT (no Power Thru)

Images courtesy of the MIDI Association - MIDI 1.0 Specification

MIDI OUT - no Power Thru
MIDI OUT - no Power Thru

NOTE: Grumpenspiel MIDI controllers (i.e. MIDI OUT) omit the optional Rc 220 resistor on the signal pin (pin 5).

MIDI OUT (with Power Thru)

MIDI IN (no Power Thru)

Images courtesy of the MIDI Association - MIDI 1.0 Specification

MIDI IN - no Power Thru

NOTE: Rb is the current limiting resistor for the opto-isolator LED. The MIDI spec image has the opto-isolator LED oriented opposite from the Eagle schematic for 6N138. MIDI pin 5 (signal) connects to opto-isolator pin 3. MIDI pin 4 (VCC) connects to opto-isolator pin 2 through Rb 220 resistor.

MIDI IN (with Power Thru)

MIDI THRU (no Power Thru)

Images courtesy of the MIDI Association - MIDI 1.0 Specification

MIDI IN - no Power Thru

NOTE: Grumpenspiel synths do not pass the IN signal to a THRU output. This schematic is included for reference only.

MIDI THRU (with Power Thru)

No sample circuit for this configuration. Grumpenspiel synths use MIDI IN only. MIDI THRU is accomplished on Power Thru only. PT splits the MIDI signal out to all the instruments directly using hex Schmitt inverters.

Connector Examples

DIN5 closeup
DIN5 closeup
DIN5 closeup
DIN5 closeup