This electronic organ is very simple to construct and can provide hours of enjoyment particularly for children. The circuit is basically an emitter-coupled oscillator composed of
T2 and T3. An squarewave voltage can be sampled from the collector of T3(X2). This signal gives the tone a clarinet character.
Without the squarewave signal, the sound produced by the emitters of T2 and T3(X4) has a violin character.
An additional vibrato signal can be added to this basic sound through switch S1. The frequency of the vibrato is approximately 6 Hz. Its amplitude is determined by the resistor R4.
The value of R4 can vary from 100 up to 300K. Try experimenting with different values.
The keys can be made of either metal plates or etched printed circuit. The trimmers P1 up tp P8 adjust the pitch of each tone.
The tones can be drastically changed by changing the value of C4.
Parts Placement Layout
Electronic Circuits volume 1.0 - Circuit Nr. 98
The complete data of the electronic circuit described above can be found in the following book and is available from Amazon.com.
Click on the image to view the book.