Tone Generator Doorbell Circuit using Dual IC 555 Timers

A circuit made to work as a Tone Generator Doorbell uses Dual IC 555 Timers making it a simple but very effective way to create a tone when someone presses the button.

The IC 555 timer is set up to work in two modes astable and monostable, which is super important for building a tone generator circuit that can power a speaker.

This circuit runs on a 9V DC supply producing a nice sound that makes welcoming guests even more enjoyable.

Circuit Working:

Parts List:

The circuit here we are using two dual 555 timer chips.

The first one IC1 is set up in a way that it only sends out a single pulse when activated.

The second one IC2 works differently by constantly switching on and off.

When you press the switch S1 it activates IC1 at pin 2 causing the output pin 3 to go high for a time that was set earlier using the values of preset resistors VR1 and VR2.

You can change the tone by adjusting the values of VR1 and VR2.

This pulse then triggers IC2 making it produce a square wave signal.

This signal goes to a 8 ohm speaker which makes a sound that continues for as long as IC1 is active.

After IC1s time is up IC2 stops working and the sound from the speaker stops too.

Formulas with Calculations:

Below are the Formulas with Calculations for Tone Generator Doorbell Circuit using Dual IC 555 Timers:

The time duration of IC1 (monostable mode) is given by:

T = 1.1 * VR1 * C1

where,

• T is the output pulse duration in seconds
• VR1 is the resistor in ohms 100k in this circuit
• C1 is the capacitor in farads 33µF in this circuit

Substituting the values:

T = 1.1 * 100,000 * 33 * 10^(-6) = 3.63 seconds

The frequency of IC2 (astable mode) is given by:

F = 1.44 / [(R2 + 2VR2) * C3]

where,

• F is the frequency in Hz
• R2 and VR2 are resistors in ohms
• C3 is the capacitor in farads

By selecting appropriate resistor and capacitor values, a suitable tone frequency for the speaker is generated.

How to Build:

To build a Tone Generator Doorbell Circuit using Dual IC 555 Timers following steps need to be followed:

• Assemble all the required components mentioned in the above circuit diagram
• Connect pin 1 of IC1 to GND
• Connect resistor R1 and S1 switch in series from positive supply to GND.
• Connect pin 2 of IC1 between resistor R1 and S1 switch
• Connect pin 3 of IC1 between pin 4 of IC2 and resistor R2.
• Connect pin 4 and pin 8 of IC1 to positive supply of the circuit.
• Connect pin 5 of IC1 to GND through capacitor C2
• Connect pin 6 IC1 to pin 7 of IC1.
• Connect pin 7 of IC1 to one leg of VR1 preset and other leg of VR1 preset connect to positive supply of circuit.
• Connect positive of capacitor C1 to pin 6 of IC1 and negative of C1 connect to GND.
• Connect pin 1 of IC2 to GND
• Connect pin 2 to pin 6 of IC2.
• Connect pin 3 of IC2 to positive of capacitor C5 and negative of capacitor C5 to one end of 8 ohm speaker and other end of speaker connect to GND
• Connect pin 5 of IC2 to GND through capacitor C4
• Connect pin preset resistor VR2 one leg to pin 7 of IC2 and other leg of VR2 connect to pin 6 of IC2
• Connect resistor R3 one end to positive supply of the circuit and other end of R3 resistor connect to pin 7 of IC2.
• Connect capacitor C3 from pin 2 of IC2 and GND
• Connect pin 8 of IC2 to positive supply of circuit

Conclusion:

This Tone Generator Doorbell Circuit using Dual IC 555 Timers is an affordable and dependable design that you can easily create with regular electronic parts.

By using both monostable and astable setups, you can control how long and how often the sound plays.

This project is great for beginners and hobbyists who want to learn more about IC 555 timer circuits and how they can be used to make sounds.

References:

Using Arduino to control NE555 to have a 2 different pulse