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.
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 cheap 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 the components first.
|IC1||CD40106||Hex Schmitt Trigger||1|
|ZD1||4.7V 0.5W||Zener Diode||1|
|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 in 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 cheap 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.
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