Detector, which is implemented on the basis K155LA3
It is not difficult to notice, all the toys and perfectly working models based on the chip K155LA3 with some piping can be collected for a day and the device will with pretty good settings. Consider a variant of the detector is based on two LC-oscillators. The scheme is part assembled on modules DD1.1-DD1.4, the second part of the circuit is a detector with voltage doubling, assembled this part of the circuit the diodes VDI, VD2 ( any high frequency germanium diodes), as the load capsule from the headset with its own impedance 2k . When a sound frequency in the headphones will change, then we can assume that what you found in the search area of the metal. As the coil and the receiving antenna using glued cardboard spool ( 30 turns of wire PEL of 0.4 mandrel with a diameter of 200 mm). Once it is working, I coil glued made of organic glass, turned mobile design, durable and comfortable. The first generator is assembled on DD1.1 and DD1.2 its frequency in the resonant circuit L1CI, GC, everything used module is damaged from any receiver. The second generator is assembled on modules DD1.3. DD1.4, it resonates at a frequency that is regulated by the inductance of the coil L2. In its chain there is a trimmer capacitor C2, it allows you to adjust the detector sensitivity. When there is a superposition of oscillations of a single generator to fluctuations in the other we hear the beating frequency, which after passing through the detector and filter (VD1, VD2, C5) are in the headphones and in our ears. As you have seen, the scheme is very small and handy device like using to search for hidden wiring in homes. KPE can be used from any transistor radio, it is there in the settings is used.
<<<< Back >>>>