The electronic organ will play only one note at a time, but the number of notes is unlimited.
Thus, different tone can be selected by touching the probe onto different keyboard contacts, so the circuit functions as a musical instrument that is played via the touch probes.
The tonal range is given by Cl, which can be altered in a large range of values. Values between 0.022 and 1 µF can be used experimentally.
A schematic diagram of the Electronic Organ is given in Fig. 1.
The circuit can be powered from AA cells or a 9 V battery. Powerful output stages can be used to drive small loudspeakers, as suggested in other projects in this site.
Each note is adjusted by the corresponding trimmer potentiometer. Current drain is only few milliamperes, extending battery life.
IC1 - 4093 CMOS integrated circuit
X1 Piezoelectric transducer, Radio Shack 273-073 or equivalent
P - Probe
S1 - SPST toggle or slide switch
B1 - 6 or 9 V, four AA cells or battery
R1 - 10,000 ohm, 1/4 W, 5% resistor
R2 to Rn+1 - 100,000 to 1,000,000 ohm trimmer potentiometers
C1 - 0.022 µF ceramic or metal film capacitor
C2 - 100 µF, 12 WVDC electrolytic capacitor
