This circuit produces two different sounds. One for the Front door and one for the Back Door. Heart of this circuit is IC 555. Here 555 is used two generate desired output. Two different sounds are generated using two switches.

When switch SW1 is pressed it will produce one type of sound here we named it as Front Door Sound.When switch SW2 is pressed it will produce one type of sound here we named it as Back Door Sound.In this Circuit Sound is generated with the help of Loud Speaker which is connected to the pin 3 i.e. OUTPUT pin of IC555. This requires 9Volts power supply. The circuit takes NO CURRENT when not producing a sound and a 9V battery will last for many months.

Circuit Diagram:

 Component Value:

  • Resistor :R1,R3 = 1 Kilo Ohm
  • Color code for 1 Kilo Ohm: Brown-Black-Red-Golden
  • R2 = 10 Kilo Ohm
  • Color code for 10 Kilo Ohm: Brown-Black-Orange-Golden
  • Electrolyte Capacitor
  • C1=1uf
  • C2=10uf
  • Tactile Switch : SW1,SW2
  •  Diode: 1N4148
  • IC1= IC 555
  • Loud Speaker
  • Battery: 9 Volts


To make complete circuit we have to follow below steps correctly.

Step 1:

IC 555 is the main component of the Circuit. Whole concept of circuit is build around 555 and its pins. Mount IC 555 on the Bread Board as shown in diagram.

Step 2:

Here IC 555 is used in Astable Mode. The important difference is that in Astable mode, the trigger pin(2)is connected to the threshold pin(6); this causes the output to continuously toggle between the high and low states.


Step 3:

Connect pin 1 of IC to Ground terminal as shown in image. Take two  horizontal slots of Bread Board for VCC and Ground respectively. Connect Black wire between pin 1 and horizontal slot of Bread Board.

Step 4:

Short pin 8 i.e. VCC  and pin 4 i.e. Reset pin of IC 555. Connect one end of Red wire to pin 8 and another end of same wire to pin 4.

Step 5:

Connect Electrolyte Capacitor of 1uF between Pin 2 of IC and Ground. Connect Positive(+) teminal of capacitor to pin 2 and Negative terminal to Ground.

Step 6:

Connect Resistor R1 of 1 Kilo Ohm to pin 6 of IC 555.

Step 7:

Connect Resistor R3 of 1 kilo Ohm on the Bread Board as shown in image.

Step 8:

Connect one terminal of Resistor R3 to pin 7 of IC555.

Step 9:

Connect second terminal of Resistor R1 to Resistor R3 through white wire as shown in image.

Step 10:

Mount Resistor R2 of 10 Kilo Ohm on Bread Board.

Step 11:

Connect Diode D1 1N4148 between Resistor R3 and R2. Connect Cathode of Diode indicated  by Silver or sometimes Black Ring  to second Terminal of R2 and Anode to Second terminal of R3.

Step 12:

Connect purple wire to another end of resistors R2 and R3. This makes connection of R1,R2,R3 to pin 7 of IC555.

Step 13:

Mount two 2 pin Tactile switch on Bread Board. Switch SW1 named as FRONT DOOR Switch and SW2 named as BACK DOOR Switch.

Step 14:

Connect pin 8 of IC to one terminal of SW2.

Step 15:

Connect Anode of Diode to one terminal of Switch SW1.

Step 16:

Connect Cathode of Diode D1 to one terminal of SW2 with the help of white wire.

Step 17:

Connect second terminal of SW1 and SW2 to one horizontal slot of Bread Board which is assigned to VCC power supply.

Step 18:

Connect Capacitor C2 of 10uf to pin 3 of 555. Connect Positive pin of C2 to pin 3 andconnect  Negative terminal of C2 to any side of Bread Board. Take precaution that Negative Terminal of C2 is not attached to any other IC pin.

Step 19:

Take loud Speaker of 8 Ohm.

Step 20:

Connect Positive Terminal of Speaker i.e. Red wire to Negative Terminal if Capacitor of C2 and Black wire to Ground.

 Step 21:

Connect Batter terminal to the Bread Board as shown in image. After that Press Sw1 and SW2 one by one and listen the difference between two sound levels.