Picture of MIDI Tester
midi tester 6.jpg
midi tester 5.jpg
If you have a MIDI device which is not responding to the controller, this handy little unit will allow you to see whether MIDI messages are actually being transmitted. Every time a message is received, the LED will blink. There is also a MIDI Thru port, so this unit can be used in a MIDI chain. This is a very useful piece of equipment for anybody who works with MIDI instruments, and it is also fairly cheap to build. My total costs were less than £10.
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Step 1: Bill of materials

Picture of Bill of materials

The following prices are taken from the website If you are in the UK I really recommend this website, as the prices are cheap and they charge a flat rate £1.50 for postage, regardless of order size.

Part Description Part Name Quantity Total
Resistor 220 Ohm 4 £0.16
Resistor 1K 1 £0.04
LED 5mm Red 1 £0.09
Voltage Regulator 7805 1 £0.28
Quad 2-input NAND 74LS00 1 £0.38
Opto-isolator 6N139 1 £0.79
Switch Miniature toggle switch 1 £0.67
Connector 5-pin 180° DIN socket 2 £1.18
Battery clip PP3 battery clip 1 £0.16
Battery PP3 9V battery 1 £0.59
Plastic enclosure 100x75x40 ABS enclosure 1 £1.94
LED bezel 5mm LED clip 1 £0.10
Wire 1m stranded core 1 £0.16
PCB PCB for project 1  
    TOTAL £6.54

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