Variable Square wave oscilator with 555 circuit

Posted on Jul 6, 2012

This is a very simple circuit utilising a 555 timer IC to generate square wave of frequency that can be adjusted by a potentiometer. With values given the frequency can be adjusted from a few Hz to several Khz. To get very low frequencies replace the 0.01uF capacitor with a higher value. The formula to calculate the frequency is given by: 1/f = 0.69 * C * ( R1 + 2*R2). The duty cycle is given by: % duty cycle = 100*(R1+R2)/(R1+ 2*R2).

Variable Square wave oscilator with 555 circuit
Click here to download the full size of the above Circuit.

In order to ensure a 50% (approx.) duty ratio, R1 should be very small when compared to R2. But R1 should be no smaller than 1K. A good choice would be, R1 in kilohms and R2 in megaohms. You can then select C to fix the range of frequencies.

Leave Comment

characters left:

New Circuits



Popular Circuits

Single Supply RS232 Interface for Bipolar AD converters
FM Wireless Mic
Audible Milliohmmeter with 555
Surround Sound Decoder circuit diagram
Alarm Digital Clock Schematic Diagram
Electronic Lock Project
high voltage white led driver
Infra-Red Remote Control Tester
TDA7056 audio amplifier circuit diagram electronic project
Infrared Fire-Cracker Igniter circuit
Automotive LED Timing Light
Arduino Thermostat