MIDI (cable) tester: A tester for MIDI connection is a real asset for many constructors. The one presented here is kept fairly simple as shown in Fig. 1.
The LED shows whether MIDI data are present where the tester is connected. Since these data consist of very short pulses, the LED must be a high-efficiency type.
To test both ends of a cable, the tester must be built in duplicate: one terminated into a socket and the other into a plug. A possible design is shown in Fig. 2.
The connectors should preferably be metal DIN types. The LED can be housed in the rubber support sleeve as shown in Fig. 3. The connecting wires to the LED must, of course, be well insulated.