Hardware Hacking 69output via a jack to the amplifier. Remember when working on the “top” side
of the chip (pins 8-14) that the capacitor leg must go between the chip and
ground, not to the + supply that shadows the ground bus on the upper side of
the board. And remember that every oscillator output signal needs a ground
connection to the jack as well.
You can use different size capacitors for each oscillator, so each of the 6 covers a
different range, from low BPM to ultrasonic pitches. You can also add a switch
that selects different capacitors for each oscillator. To mix more than one
oscillator to a single jack, connect each output to the jack through a resistor of
about 10kOhm -- don’t jumper them together with plain hookup wire, since that
causes the dreaded short circuit and can damage the chip. Or you can use the
home-made tilt switch from Chapter 17 to select different oscillator outputs as
you wobble the circuit.
If you substitute a component called a “diode” for the resistors to do the mixing
you’ll find that the individual oscillators interact and distort, producing a “ring
modulation” type sound.