The installation on the vehicle any device that improves traffic safety, can only be welcomed. In particular, to improve the mutual orientation of pedestrians and drivers allow alarms reversing. Uncomplicated such the device prompts the author of published articles here.
Many cars of foreign production and domestic cars are already equipped with speech sound alarms, warning pedestrians on the movement of vehicles in reverse. Often, however, the sound quality of the warning phrase is that parse its content little people can, even if it sounds in Russian. But if it sounds at foreign, it is simply incomprehensible to most pedestrians.
In my opinion, tone or three-tone signal probably will attract the attention of the pedestrian. In addition to manufacture such a device is easy.
In the detector, the circuit of which is shown in Fig. 1, used a specialized chip CRUZ, designed for use in call the host telephone. The composition of the chip includes two generator - clock and tone, and a controllable frequency divider, a counter sound of parcels and the node management.
The tone generator generates a voltage base frequency, which can change the appropriate selection of the values of castorocauda chain R4C4. Under these the scheme the values of these elements tonal frequency is about 50 kHz.
A controllable frequency divider can operate with three alternating fixed factors of division. The order of their rotation (tonal combination parcels) determine the supply of certain voltage levels on the inputs N1, N2 of the chip.
The speed of rotation of parcels depends on the clock frequency, which is set the choice of the values of the circuit R3C3. Indicated in the figure correspond to the values of the frequency about 0.3 Hz.
Generated a sequence of tone signals from the output of L1 is supplied to the base of transistor VT1 of the current amplifier, which loading is dynamic head BF1.
More detailed information about the device and the operation of the chip can KRUG be found in the book of Kozluca A. and Sakova A. "Handbook of the device and repair telephones foreign and domestic production". - M., 1993.
Power to the chip is supplied with parametric stabilizer VD3R1, since the frequency of the generator is highly dependent on the supply voltage. Amplifier transistor VT1 for more volume eats side voltage. Diode VD1 protects the detector from connecting to the onboard network in incorrect polarity.
All parts of the device, in addition to the dynamic head BF1, mounted on a printed Board of foiled fiberglass with a thickness of 1 mm the Drawing Board pictured in Fig. 2. The chip soldered to the printed conductors.
Diode KD105B replace any of the series. The Zener diode will fit any low-power for a voltage of 9...10 V. the Dynamic head, you can use any power 1 or 2 watts with a coil resistance of 6.5...8 Ohms.
Cost and the dynamic head set in plastic box suitable the size and fasten it in the trunk of a car. Connect the detector to the lamp lamp, signaling the reverse gear.
The establishment of the motion detector begin with installation of the smart mode the current amplifier transistor VT1. To do this, choose the resistor R5 such that at an acceptable volume of the sound signal does not overheat the transistor. In the conclusion, if necessary, adjust the tonal frequency and clock generators, selecting resistors R4 and R3, respectively.
Author: R. Ushakov, Zelenogorsk, Krasnoyarsk region