0.01Hz To 500kHz Adjustable Tone Frequency Decoder Using LM567

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3 Adjustable Tone Frequency Decoder Circuit

In this project, we are making a 0.01Hz To 500kHz Adjustable Tone & Frequency Decoder Using LM567. This circuit detects a specific tone and frequency from 0.01 to 500KHz, the main component of this circuit is an LM567 IC.

LM567 is a general-purpose tone and frequency detector IC and it is highly stable. There are different versions available of this chip with the same ending number (567) like NE567, KIA567, etc. The internal circuitry of all of these ICs is the same. This IC is made to perform in such a way that it locks a specific tone or frequency also called center frequency and whenever a similar frequency is detected by the input of this IC, the output goes low. The circuit is very simple and can be built easily as it is only using an IC, a battery, and a few discrete components.

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Hardware Components

The following components are required to make an Adjustable Tone Frequency Decoder Circuit

S.no	Component	Value	Qty
1.	Input Supply DC	5.9V	1
2.	IC	LM567	1
3.	Resistor	12KΩ, 4.7KΩ	1,1
4.	Electrolytic Capacitor	2.2µF, 1µF	1
5.	Ceramic Capacitor	0.1µF	1
6.	Variable Resistor	50K	1

LM567 Pinout

For a detailed description of pinout, dimension features, and specifications download the datasheet of LM567

Adjustable Tone Frequency Decoder Circuit

Working Explanation

The minimum and maximum voltage for operating this IC are 4.75 volts to 9 volts DC, this circuit can be operated at any voltage from 5-9 volts DC. The center frequency of this IC is adjusted and set by a 50K ohms variable resistor. The input frequency or tone is detected at pin 3 (input pin) of the IC. whenever the required or center frequency is detected by the IC its output will go low. This IC’s output can drive a load of around 100mA therefore the relay switch can be directly derived from the output pin of this IC. The output can also be fed to a digital circuit or a microcontroller for further processing.