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High power siren circuit using CD40106

If you are looking for a simple siren sound that high power output and very noisy. This may be the best choice for you. It uses a digital IC, so easy to use CD40106 hex inverter gate, and four power transistors to increase current out of horn speaker 20 watts, 8 ohms at 12V battery power.

How This Circuit works
In the circuit below. First of all, connects the 12V power supply to the circuit.

High power siren circuit using CD40106

They have two frequency generator circuits.

  • The first part includes  IC1/1 (pin 9,8), R2, C2 to produces the frequency of 1Hz.
  • The second part includes  IC1/2 (pin 13,12), R2 and C3.

Both frequencies are mixed into a modulation signal with  R3, R4, C3, ZD1.  Until there is square wave frequency in changing of two-level frequencies are like common sirens.  It comes out of the second part at pin 12.

Next, It comes to the others pins of IC1 to buffer the signal.  After that, to the power amplifier section.

They include 6 transistors that set in 2 group.

  • First set, Q1, Q4, and Q5
  • The second set, Q2, Q3, and Q6

Both sets will alternately work. To drives the high sound signal to a speaker.
This causes transistor uses low power. But they make high power to output or very loud siren.

Building High power siren circuit

Let’s build them. You should get components first.

 ListNameDetail Amount 
IC1 CD40106Hex Schmitt Trigger1
D1 1N5402 Diode1
 ZD1 4.7V 0.5W Zener Diode1
 C1,C2 1uF 25V Electrolytic2
C4 47uF 25V Electrolytic1
C3 0.001uF 50V Ceramic1
R1 1M 0.25W, 5% Resistors  1
R2 220K 0.25W, 5% Resistors 1
R3, R5 2.2M 0.25W, 5% Resistors 2
R4, R6, R7 100Ω 0.25W, 5% Resistors 3
 Q1, Q2 BC337 0.6A 40V, NPN transistors 2
 Q3, Q4 TIP32 4A 40V, PNP transistors 2
 Q5, Q6 TIP31 4A 40V, NPN transistors 2
 SP1 8Ω , 10W Horn Speaker 1


This circuit is small size. So you can assemble them on the perforated board.
You should solder the component onto PCB carefully. Even IC, transistors, diodes, and the device such as polarized  Electrolytic capacitors, must be correct.

How to use its
This is a super siren is small. It can be applied compatible with various theft protection circuit, decidedly, For example, to prevent a home burglary, car theft protection, or want to use different alarm sirens.

This Post Has 4 Comments

  1. hi
    i need some kits with pcb files

  2. Hello,

    I don’t see what are the values for R4 or R6. I also see that R3 and R5 shown twice in the part list.

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