Toy Organ Circuit using 555 Timer IC

Have you ever tried to design a circuit that produces sound? Here is the circuit that produces five tones. This is a simple toy piano circuit with 555 timer. We can also use this circuit as a Machine gun.

Toy Organ Circuit Principle:

Main heart of this circuit is 555timer IC. The 555 timer is operated in astable multivibrator mode. In astable multivibrator mode, the circuit produces accurate free running waveforms, which can be adjusted.

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The circuit consists of six 1 kohm resistors connected in series. There are six buttons connected in the circuit. When one button is pressed it produces a tone. Similarly, six buttons produce six different tones. That means, it just works as a toy piano. When the first button from right is pressed it produces high pitch tone. When the last button is pressed it delivers a low tone. This is because of the resistance connected to the buttons. The low thresh hold voltage obtained at the sixth pin slows the charging and discharging of 10 micro farad capacitor at the speaker. As the resistance value increases voltage at the threshold pin decreases and low frequency passes through speaker.

Toy Piano Circuit Diagram:

Circuit Diagram of Toy Organ 

Circuit Components:

• 555 Timer IC
• 6 Resistors – R1 to R6.
• Potentiometer – RV1
• Capacitors – C1 and C2
• Speaker of capacity 8ohms.

Toy Piano Circuit Design:

The 555 IC is a timer IC that produces frequency. 555 timer IC is operated in astable multivibrator mode. The supply voltage VCC is 6V. Six 1k resistors are connected in series. Second and sixth pins are shorted to allow retriggering of 555 timer IC after every timing cycle. These two pins are grounded through a capacitor. Fourth pin is reset pin it is shorted with eighth pin i.e. VCC to avoid sudden resets. Seventh pin is discharge pin. It is connected to series resistors through a variable resistor. Output is taken from third pin. The obtained frequency is applied to the 8 ohms speaker through a 10 microfarad capacitor.

How to Operate Toy Piano?

Initially Power the circuit. Now press the first button from right. It produces a tone with high pitch. Now press the second button it’s pitch is slightly lower than the first button. Now press the next button. Likewise, press all the buttons in order to listen the tones produced by them. This is similar to tones produced by a piano. At a time only one button can be pressed.

Applications of Toy Organ Circuit:

• It is used to produce different types of tones and sounds by changing the resistor values.
• We can use it as a best birthday gift for the kids.
• We can also use this circuit as a Machine gun by changing the resistor and capacitor values.

source:http://www.electronicshub.org