THE SOUND WILL BE LOUDER

In order to obtain a sound signal of high power (10 – 20W) from the simple Assembly of a sound generator, does not require complex amplifiers WOOFER.
The generator on the popular chip KP1006BU1 (DA1) is enabled by almost classical scheme and in the description is not needed. The output frequency is approximately 1000 Hz. It can be considerably corrected by changing the values of the elements C2 and R2. The output frequency in this circuit is calculated by the formula:
F(kHz) = 1,44/(R1 +2xR2)xC2, where the resistance of the resistors R1, R2 in ohms, and the capacitance of the capacitor C1 is in microfarads.

The IC output (pin 3 DA1) cannot provide significant power, so the FET VT1 is implemented power amplifier. You can, of course, be applied to ordinary bipolar transistor, such as the type КТ819БМ (by connecting its emitter to ground, collector to BA 1, base to terminal 3 DA1 through a current limiting resistor 470 and 820 Ohms). However, in this case a field-effect transistor as a power amplifier is better, because in the open state, the transition “drain — source” has less resistance, which means that FET will be negligible power loss and accordingly greater efficiency.

Details

Instead of the MOSFET BUZ11 can include similar electrical characteristics of field-effect transistors IRF521, IRF540, setting them on the heat sinks (at a power dynamic head 5 watts or less).

All fixed resistors type MLT-0,25, MF-25.

The dynamic head of BA1 — any designed for a capacity of 10 — 20 W with coil resistance of 4 ohms. With a larger resistance, e.g. 8 Ohms, power is proportionately reduced.

Circuit diagram of power increase of the output signal of the sound generator

Oxide capacitor C1 is introduced in the scheme for smoothing of power supply. The type K50-29 or similar. Non-polar capacitors C2, Sz 0 type KM-6, K10-17, CT-4-23, KWS or similar. The Sz condenser connected to the terminal 5 DA1 to protect against interference output control voltage in this case can be deleted from the scheme.

Power needed stable, with an output voltage in the range 9 — 15 (the higher the voltage, the higher output power of the amplifier) and a current 7 — 10 And when using as BA1 high-performance speakers 10 — 20 watts.

It is limited only by imagination and the specific objectives of Amateur radio. Practically, the device can be applied quite widely. For example, where you want a loud notification sound (on the street) when conducting any activities. One example is the use of the device as the audible alarm of the protected objects. This dynamic head of BA1 is directly on the street. With the help of this device you can protect not only warehouses and hospitals for inmates, various insulators, and polygons.

A. KASHKAROV, St. Petersburg