A simple electronic toy piano can be easily constructed using transistors and a few discrete components. The circuit consists of two parts.
The first part is of transistors that are wired to form an Astable multivibrator. The audible frequency range of humans is from 20Hz to 20 kHz, so we are going to generate frequencies in this range by adjusting the variable resistor. The second part is the amplifier. The generated frequency from the transistors is then fed to the amplifying circuit where the signal is amplified and then we get the output tone from the loudspeaker. This circuit is capable of generating seven different tones and works similarly to an electronic piano.
Hardware Components
The following components are required to make Electronic Organ Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Battery | 9V-12V | 1 |
| 2. | Transistor | 2N3904, 2N3906 | 2, 1 |
| 3. | Ceramic capacitors | 47nF, 33nF | 1, 1 |
| 4. | Speaker | 8Ω | 1 |
| 5. | Push switches | – | 7 |
| 6. | Variable resistors | 500K | 7 |
| 7. | Resistors | 91R, 1K, 56K, 47K, 4.7K | 1, 2, 1, 1, 1 |
2N3904 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of 2N3904
Electronic Organ Circuit
Working Explanation
The operating voltage of the circuit is 9V to 12V DC. The first stage of the circuit consists of two NPN Transistors Q1 and Q2 (2N3904), connected to form an astable multivibrator. The signal generated by the first stage goes to the second stage. The second section is a PNP transistor (2N3906) that acts as an amplifier and is used to amplify the output sound of the circuit. The circuit is using seven push switches and a 500K variable resistor to generate 7 different tones. When operating the circuit first time each 500K variable resistor is adjusted to a value to get the desired sound frequency. When all are adjusted you are ready to go with your electronic organ project. An 8-ohm speaker is used in the circuit to get the output.
Applications and uses:
- It is used to produce seven different types of tones and sounds by changing the resistor values.
- Best toy for kids.
- We can also use this circuit as a Machine gun by changing the resistor and capacitor values.
