Description
Turn your guitar into a MIDI instrument, control keyboards or synth with the pluck of a string!
This unit is ‘monophonic’, meaning that only one note can be played at a time, but still very useful for solo playing. No modifications to the guitar are required as it makes use of the existing pickups. Here are a few tips for getting the best results out of the unit:
Always use a plectrum. This gives good stroke peaks for the software to read.
Make sure that only one string is making a sound, i.e. the one you want! Open ‘ringing’ strings, especially the lower pitch ones will cause frequency beating with the desired string. Muting strings with the palm of your hand, hemps to deaden the previous notes.
Do not pluck too hard, some high output pickups will overload the op-amp and cause the waveform to clip, this reducing the size of the peaks against the background harmonics. Keep an eye on the ‘peak’ LED and if it turns on a lot, reduce the guitar volume or pick softer.
It doesn’t take much practice to become good at producing reliable MIDI note data, and as a by-product it improved your picking technique.
Distributed with permission of Electron Publishing, as featured in October 2009 Practical Electronics Magazine: https://www.epemag3.com/proj/1009.html
Specification
- MIDI Out DIN
- 6.35mm (1/4”) Line In – Guitar In
- 6.35mm (1/4”) Line Out – Guitar Thru
- Peak LED
- MIDI Note LED
- Powered by 9v Battery
- PIF16F88 Microcontroller
- Measurements: 58mm x 93mm x 23mm
Build Instructions
| Designator | Name | Quantity |
|---|---|---|
| Semiconductors | ||
| IC1 | TL072 dual FET op amp | 1 |
| IC2 | PIC16F88-I/P microcontroller, pre-programmed | 1 |
| IC3 | 78L05 +5V 100mA voltage regulator | 1 |
| LED1 | 5mm red light emitting diode | 1 |
| LED2 | 5mm green light emitting diode | 1 |
| Capacitors | ||
| C1, C3, C6, C7, C8 | 100 nF ceramic Capacitor | 5 |
| C2, C5 | 22 uF radial electrolytic, 35V Capacitor | 2 |
| C4 | 4.7 uF radial electrolytic, 63V Capacitor | 1 |
| Resistors | ||
| R10, R11 | 100 Ohm Resistor | 2 |
| R12, R13 | 220 Ohm Resistor | 2 |
| R3, R4 | 4.7k Ohm Resistor | 2 |
| R9 | 15k Ohm Resistor | 1 |
| R7 | 18k Ohm Resistor | 1 |
| R8 | 27k Ohm Resistor | 1 |
| R1 | 180k Ohm Resistor | 1 |
| R5 | 470k Ohm Resistor | 1 |
| R2 | 680k Ohm Resistor | 1 |
| R6 | 1M Ohm Resistor | 1 |
| IC1-1 | 18-pin DIL IC Socket | 1 |
| IC2-1 | 8-pin DIL IC Socket | 1 |
| SK3 | 5-way 180 type A DIN socket, PCB mounting | 1 |
| SK1, SK2 | 6.5mm (1/4in.) PCB mounting stereo jack | 2 |
| +V, GND | 9V Battery Clip | 1 |
Resistor Colours
Board Layout
