• Skip to main content
  • Skip to primary sidebar

Homemade Circuit Projects

Need circuit help? Post them in the comments! I've answered over 50,000!

Blog | Categories | About | Contact | Calculators-online
You are here: Home / Home Electrical Circuits / Two Tone Door Bell Circuit

Two Tone Door Bell Circuit

Last Updated on November 15, 2023 by Swagatam Leave a Comment

The electronic 2 tone door bell circuit is designed around the popular IC 555. The IC 555 is extensively applied in numerous varieties of timers and also as a basic oscillator circuit. In this particular project both the timer and the oscillator functions of the IC are utilized.

Table of Contents
  • How the Circuit Works
  • Parts List

As soon as the indicated push-button is pushed with our finger, the IC 555 begins oscillating with a specific frequency (tone), and as soon as the push-button is released, the frequency changes, modifying the sound of the tone, and the IC now continues generating this second tone for a specific amount of time period, as determined by the RC time constant of the IC.

Hence, when the bell button is pressed once, we get a two-tone doorbell sound from the speaker which is directly attached to the IC pin#3, and operated directly by the IC 555 output.

How the Circuit Works

Referring to the diagram below, the working of this two tone doorbell circuit can be understood with the help of the following points:

The capacitor C2 gets charged at the start, and the charge reaches the supply level of +9V through resistors R2, R3 and R4.

two tone door bell circuit

However, because the upper end of the capacitor is linked with both pin#2 and pin#6 of the IC.

Therefore, as soon as the voltage across the capacitor tends to reach 6V level, the two internal comparators of the IC gets above their threshold level, causing the IC 555 at pin#3 to go low, which in turn results in the internal transistor of the IC to switch on.

The action short circuits the pin#7 of the IC to ground.

But, since pin#7 is hooked up with the junction of the resistors R3 and R4 and C2, now begins getting discharged by means of the resistor R4.

During this process as soon as the voltage stored inside C2 tends to drop below 3 V, causes the output of the IC to yet again go high, switching OFF the internal transistor of the IC.

This in turn immediately causes C2 to start charging again by means of the resistor R2, R3 and R4.

This sequence of action goes on repeating continuously, which causes the generation of triangular waveform across C2, creating a train of pulses at the IC output pin#3.

This train of pulses coming out from the pin#3 of the IC can be seen configured with a loudspeaker by means of the capacitor C3.

The C3 capacitor ensures that the dc component present in the pin#3 output voltage does not reach the loudspeaker and thus prevents the loudspeaker from burning.

The capacitor C2 generates the triangular waveform as it charges through 3 V to 6 V and while discharging from 6V to 3V.

If you desire to change the pitch tone of the two tone door bell circuit, to a different tone you just have to tweak the values of the resistors R2, R3, R4 or simply the change the value of C2 appropriately until the desired tone output is achieved.

Parts List

two tone door bell circuit

You'll also like:

  • 1.  Digital Theremin Circuit – Make Music with your Hands
  • 2.  Build this Open Baffle Hi-Fi Loudspeaker System with Crossover Network
  • 3.  How to Build a Simple Cloth Dryer for Rainy Season
  • 4.  Simplest AM Radio Circuit
  • 5.  Simple Intercom Circuit [2 way]
  • 6.  How to Build an Ozone Water/Air Sterilizer Circuit – Disinfecting Water with Ozone Power

About Swagatam

I am an electronics engineer with over 15 years of hands-on experience. I am passionate about inventing, designing electronic circuits and PCBs, and helping hobbyists bring their projects to life. That is why I founded homemade-circuits.com, a website where I share innovative circuit ideas and tutorials. Have a circuit related question? Leave a comment.... I guarantee a reply!

Previous Post: « Bridged Amplifier Circuit using LM380 Circuit
Next Post: Bench Amplifier Circuit »

Reader Interactions

Need Help? Please Leave a Comment! We value your input—Kindly keep it relevant to the above topic! Cancel reply

Your email address will not be published. Required fields are marked *

Primary Sidebar

Subscribe to New Circuit Ideas

Categories

  • Arduino Projects (87)
  • Audio and Amplifier Projects (132)
  • Automation Projects (17)
  • Automobile Electronics (101)
  • Battery Charger Circuits (83)
  • Datasheets and Components (104)
  • Electronics Theory (143)
  • Free Energy (37)
  • Games and Sports Projects (11)
  • Grid and 3-Phase (19)
  • Health related Projects (25)
  • Home Electrical Circuits (12)
  • Indicator Circuits (14)
  • Inverter Circuits (87)
  • Lamps and Lights (142)
  • Meters and Testers (69)
  • Mini Projects (46)
  • Motor Controller (64)
  • Oscillator Circuits (27)
  • Pets and Pests (15)
  • Power Supply Circuits (108)
  • Remote Control Circuits (50)
  • Security and Alarm (64)
  • Sensors and Detectors (101)
  • Solar Controller Circuits (59)
  • Temperature Controllers (42)
  • Timer and Delay Relay (49)
  • Transmitter Circuits (29)
  • Voltage Control and Protection (37)
  • Water Controller (36)

Calculators

  • Battery Back up Time Calculator
  • Capacitance Reactance Calculator
  • IC 555 Astable Calculator
  • IC 555 Monostable Calculator
  • Inductance Calculator
  • LC Resonance Calculator
  • LM317, LM338, LM396 Calculator
  • Ohm’s Law Calculator
  • Phase Angle Phase Shift Calculator
  • Power Factor (PF) Calculator
  • Reactance Calculator
  • Transistor Astable Calculator
  • Transistor base Resistor Calculator
  • Voltage Divider Calculator
  • Wire Current Calculator
  • Zener Diode Calculator
  • Filter Capacitor Calculator
  • Buck Converter Calculator
  • Boost Converter Calculator
  • Solar Panel, Inverter, Battery Calculator
  • Wire Current Calculator
  • SMPS Transformer Calculator
  • IC SG3525, SG3524 Calculator
  • Inverter LC Filter Calculator

People Also Search

555 Circuits | 741 Circuits | LM324 Circuits | LM338 Circuits | 4017 Circuits | Ultrasonic Projects | SMPS Projects | Christmas Projects | MOSFETs | Radio Circuits | Laser Circuits | PIR Projects |

Recent Comments

  • Swagatam on Battery Deep Discharge Protection Circuit
  • Swagatam on 10 LED Tachometer Circuit Diagram
  • Drew Adare on How to Collect Free Energy from Atmosphere
  • Göran on 10 LED Tachometer Circuit Diagram
  • Abdulmajid Haruna on Laptop Power Bank Circuit

Company

  • Privacy Policy
  • Cookie Policy
  • About Me
  • Contact
  • Disclaimer
  • Copyright
  • Videos
  • Sitemap

Social Profiles

  • Twitter
  • YouTube
  • Instagram
  • Pinterest
  • My Facebook-Page
  • Quora
  • Stack Exchange
  • Linkedin
  • © 2025 · Swagatam Innovations