Powerful siren using transistors. DIY air raid siren with two transistors 12 volt siren circuit

consists of two square pulse generators. The first generator is assembled using elements DD1.1 and DD1.2. It generates pulses of a fixed repetition rate (about 0.5 Hz), which is determined by the ratings of the C1R2 parts. Resistor R1 protects the inputs of element DD1.1 from overload.

An integrating circuit R3R4C2 is connected to the output of the first generator, which generates a sawtooth voltage that controls the frequency of the second generator. The speed of rise and fall of the siren frequency depends on the ratings of the parts of this circuit, and the limits of its change depend on the ratio of the resistances of resistors R3 and R4.

The second generator is the siren tone generator. It is made on elements DD1.3 and DD1.4 according to a symmetrical multivibrator circuit. The repetition rate of the generator pulses and their duration depend on the values ​​of resistors R5, R6 and capacitors SZ, C4.

Emitter followers on transistors VT1-VT4 are connected to the second generator. This unusual connection of transistors resembles two bridge circuits, one diagonal of which receives the input signal, and the other is connected to the dynamic head BA1. Such a cascade allows you to quadruple the output power of the siren compared to a conventional power amplifier based on emitter followers and connect a dynamic head without an oxide transition capacitor.

Fig. 1 Electronic siren circuit

The device uses fixed resistors MLT-0.125, capacitors KM-6 (C1), K53-1 (C2), KM-5 (SZ, C4). Transistors can be any other of the series indicated on the diagram. Instead of the K176LA7 microcircuit, K176LE5, K561LA7, K561LE5 will be suitable without any changes in parts and printed circuit board. A printed circuit board was developed for these parts, the drawing of which is shown in Fig. 2.

The board is placed in the body of the toy being assembled and connected to it with flexible mounting conductors: an SAI switch, a power source (for example, a 3336 battery) and a BA1 dynamic head (power 0.1-0.5 W with a voice coil with a resistance of 6-10 Ohms).

Before setting up the device, temporarily turn off the dynamic head. Then power is supplied to the siren and the operation of the first generator is checked with an oscilloscope - there should be rectangular pulses at pin 4 of element DD1.2. After this, a sawtooth signal (with a swing of at least 2 V) is observed on capacitor C2. Next, make sure that there are rectangular pulses at pins 10 and 11 of the microcircuit, the repetition frequency of which changes periodically (with a frequency of approximately 0.5 Hz). The same signal should be at the emitters of all transistors. Now you can connect the dynamic head and use the siren for its intended purpose.

Fig.3 Output stage

If you need a more powerful siren, assemble an additional attachment (Fig. 3) and connect it instead of the dynamic head. And connect the BA1 head of the appropriate power to the output of the set-top box (you can use an emitter from a megaphone). The siren itself, as before, is powered by a 3336 battery, and the set-top box is powered by a powerful source (for example, a battery) with a voltage of 10... 13 V. The transistors of the set-top box must be installed on radiators, the area of ​​which depends on the required output power of the set-top box.

V. Koretsky, Moscow

The circuit of this intermittent siren is very simple, I found it several years ago on the Internet, then the board was soldered and tested in practice. It is based on a generator based on transistors VT1 and VT2, assembled according to the circuit single-ended multivibrator. How it works: when you press the SB1 button, the sound of a siren is heard with an ever-increasing pitch, after releasing the button the pitch decreases and the siren goes silent. The sound tone can be changed by selecting capacitor C2, or taking several capacitors by connecting them in series, parallel or in a mixed connection. I took the speaker with a power of 0.1 W, it used to be in some Chinese toy. The case did not allow for a larger speaker. Then I didn’t etch the board, but made it by cutting grooves.

When testing the siren, I experimented with different speakers, power from 0.1 to 5 W, resistance 4-8 Ohms, all worked fine. The supply voltage was 9-11 volts, it can be powered from " crowns”or if you can find 2 series-connected batteries on sale 3R12(Soviet name 3336 ) at 4.5 volts, the latter will last longer.

You can also power it from a Chinese power supply delivering 9-12 volts. If someone doesn’t want to manually set the tone of the sound using a button, I think you can connect a symmetrical multivibrator instead of a button, then when the transistor of the multivibrator is open, the siren will sound, and when the transistor is closed, it will be silent accordingly. Here is a photo of the finished device:

I installed film capacitors simply because I had them, but I think ceramic capacitors would have worked just as well here. Transistors can also be taken of any appropriate structure. In standby mode, with switch SA1 closed, the device consumes little current, which allows it to be used as an apartment bell if desired. When the SB1 button is pressed, the current consumption increases to 40 mA. Here is a drawing of the printed circuit board of this siren:

In today's article I want to talk about the air raid siren

The circuit is quite simple and will not be difficult to assemble

I came across a diagram of the Air Raid Siren from the site RadiKot.Ru

The circuit is cool and I decided to assemble it, but as you can see, in order to change the key, you need to press a button. I thought about how this could be automated, I thought about it and came up with it. Remember, I wrote about , and that’s what will work in this scheme. This is what I got now

Minimum details, maximum effect:

R1 = 68k
R2 = 51k
R3 = 22k
R4.5 = 10k

VT1= KT315
VT2= P217
VT3,4= S9014

The speaker used was 5 W 16 Ohm from a disassembled TV

I was pleased with the result, but the neighbors screamed for a long time afterwards. It's good that they don't know who did it. Good luck with the build

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Proposed electronic device A homemade siren can be used anywhere. For example, for signaling in case of unauthorized opening of a room or a certain area, or simply for entertainment purposes.

The areas of application for such a siren are limitless and depend only on a person’s ideas. By and large, this device simply imitates an air raid siren. Both novice radio amateurs who are interested in DIY electronics and specialists will be able to assemble such a “miracle.”

Siren circuit:

The picture shows circuit diagram sirens

VT1 – transistor KT315 (KT3102, transistors from the MP35-MP38 series are also suitable)

VT2 - KT814 (KT816, KT835, KT837) – with any letter index

BA1 – any speaker. The remaining details are clearly visible in the diagram.

How to make a siren - instructions

All the necessary details on how to make a siren are shown in the photo. Both large and miniature speakers can be used as speakers. To power the siren, a 9-volt Krona battery will do. Any button (I took it from a laser pointer). Resistors can be of any power. Electrolytic capacitor C1 must be designed for a rated voltage of 16 V. Transistors The location of the contacts of the transistor KT315 and KT814 is shown in the figure. During assembly, it is necessary to correctly connect the contacts (base, collector and emitter) of the transistors, as shown in the diagram and figure. Otherwise, the transistors may fail. The letter index can be anything. Assembly As contacts for the device, I used copper wires with insulation 30-40 cm long. The ends of each wire were stripped and treated with rosin and then tin. We slowly assemble according to the diagram, soldering the prepared wiring to each part. It is worth noting that you should not overheat the transistors, as this will lead to their malfunction. The electrolytic capacitor must be soldered as shown in the diagram (there will be a + or - sign on its body near the side contact).

The principle of operation is this: when you press the button, the sound frequency increases, when you press it, it decreases. The diagram shows that even with the contacts open, the circuit is connected to power (the crown is slowly discharged). This can be corrected by connecting an additional switch. This is what a homemade siren looks like after everything is soldered correctly. IN in this case I connected a miniature speaker (see photo). Such a siren will not be very loud, but absolutely compact. The case for such a device can be used not large. When connecting a speaker of higher power and larger size (see photo), the siren with your own hands will be quite loud. For such a siren it is necessary to find a larger housing. If you want to use the siren as an alarm or doorbell, then instead of the crown it is advisable to connect a power supply with an output DC from 9 to 12 volts.

Good luck with your DIY siren assembly!