Schematics

Audio Output Circuit

In our electronic piano there are two external circuits input keyboard and output speaker. The first is the output circuit, we used transistor Q1 for a simple audio amplifier and the transistor Q2 is a volume level control by PIC16C84 pin RA2 pulse width.

Keyboard Input Circuit

The following is the circuit used to interface the keyboard with the PIC16C84 port B RB4,RB5,RB6, these pins relate to the three columns. To determine which key has been pressed, we used these pins with pull-up resistor to Vcc, if a key has been pressed the input will detect a low signal.

Piano Circuit

The completed electronic piano schematic as follows:

click here is the old circuit
click here is the modify circuit

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