Transistor Organ

This simple circuit can provide hours of enjoyment as you learn tunes, play duets or just make some really weird sounds by pushing all the buttons at once. You have probably seen this ciruit before, it is fairly common. I have seen it in several books. The best thing about the circuit is that you can tune each individual note, or go to a whole new octive by changing one capacitor (C1). Because of this, it is possible to from an entire Transistor Organ ensemble.

Schematic

This is the schematic of the Transistor Organ

Parts

R1-R8_______250K Trim Or Regular Pot
R9,R12______100 Ohm 1/4 W Resistor
R10_________10K 1/4 W Resistor
R11_________220 Ohm 1/4 W Resistor
R13_________5K Pot
C1__________.01uF Capacitor
C2__________.1uF Capacitor
Q1__________2N4891 Unijunction Transistor
Q2__________2N2222 Or 2N3904 Transistor
S1-S8_______SPST Switch
SPKR________8 Ohm 2 W Speaker
MISC________Wire, Circuit Board, Knobs For Pots.

Notes

1. You can tune the organ to any instrument by adjusting R1-R8. I used a clarinet to tune mine, but you can of course use any instrument you wish.

2. The circuit may drain a 9V battery fairly quickly at full volume. You may remove R11 for even more sound.

3. You can rig up a relay and a foot switch to change C1 while your playing.