Many devices, allowing you to locate and hidden damage the wiring consists of a sensor-antenna receiving the AC electric field, amplifier and sound or dial indicators. For effective operation of a capacitive antenna, the amplifier must have high input the resistance that often by the incorporation of the input source follower a field effect transistor [1-3].
In the apparatus described it is proposed to use high input resistance CMOS IC, which is for amplifying an analog signal is translated into a linear mode [4]. In Fig.1 shows a diagram of the seeker, which allows to detect the location and damage of hidden wiring, radio network, broken wires in unshielded cable, a malfunction in electrovalence.
The sensor antenna W1 is a ring with a diameter of 2 cm of insulated installation of wire, shielded wire is connected to the input of the device. The screen wire on the sensor is isolated, and the device is connected to the common wire. Unshielded wire should be of a minimum length. The sensor signal served on pins 8 and 9 of the chip DD1. The element DD1.1 chip is transferred to linear mode through a negative feedback through resistors R1, R2. The capacitor C2 and variable resistor R2 allow you to adjust the depth negative feedback by changing the input impedance, and hence the sensitivity of the device. The capacitor C1 removes the excitation of the amplifier. The exit of the element DD1.1 is connected directly to the inputs of elements DD1.2...DD1.4, resulting in the linear regime of these elements is set automatically. Reinforced DD1 chip signal through a capacitor C3 is supplied on connector X1 to be connected to high impedance phones (TONE-1, TONE-2) or subscriber loudspeaker.
In Fig.2 shows a diagram of the seeker, in which the sensitivity is adjustable a variable capacitor C1, and the sound emitter is a piezoelectric radiator HA1.
To increase the volume of the piezo oscillator is included in a bridge circuit. The capacitor C1 (Fig.3) made of wire of a printed circuit Board (Fig.4). Dielectric spacer capacitor cut from the film, which is removed emulsion layer. The spring can be rented from a ballpoint pen.
Powered device battery "Krona" or 7D battery-0,125 chips Instead of D. CLA you can use CLE. Use chips series gave K several of the worst results. Variable resistor R2 (Fig.1) - any type resistance 10...100 kω. As the capacitor C1 (Fig.2) can use one of the sections KPE radio.
Required for installation the limits of the capacitance in series with KPE include capacitor 100...200 pF. The size and shape of the sensor antenna is selected depending on the required sensitivity and ease of use of the appliance. You can make several interchangeable sensors of different sizes and shapes.
The method of operating the seeker has no peculiar features and are similar to those described in [2,3].
Literature
Author: L. D. Bogoslavets, Cherkasy region