Bagpipes

If you look at the Bagpipes circuit diagram you will see that it consists of the same audio oscillator and similar timing components as the Wonky Wire circuit. The Bagpipes is, however, capable of producing eight different tones from about 5kHz (5000 cycles per second) down to about 300Hz.

To use the Bagpipes the stylus wire is moved up and down the network of resistors R1 to R8 which make up the keyboard. These resistors form a voltage divider.

The voltage at the end of the stylus therefore changes as each keyboard resistor is touched in turn. At the top of the keyboard the stylus voltage is 9 volts whereas at the bottom it is about 1 volt. A higher voltage speeds up the charging of the capacitors and produces a higher note. A lower voltage slows down the charging of the capacitors which results in a lower note.

Notice that R10 connects R9 and VR1 to ground to disable the oscillator when the stylus is not being used.

VR1 is a variable resistor to enable some tuning of the Bagpipes.

Skill Level 2. This kit requires soldering of components to the PC board while building.

• This kit requires soldering of components to the PC board while building. 
• Soldering required

Ages 13+