Unlike the 25 watt system presented by earlier, its lighter the variant is distinguished by simple circuitry, the absence of scarce parts and a relatively low and safe voltage in the transmission line. In addition, in this case, instead of a separate secluded container, you can use the receiver body. The whole design is quite simple and easy to set up. The transmitter circuit of this device is shown in Figure 1, the receiver - in Figure 2.

Fig.1. Schematic diagram of a 4W longitudinal wave transmitter

The transmitter works as follows. From the PS1 power supply, 12V power is supplied to it, which are fed to the master oscillator on the DG1 microcircuit, through the high-pass filter R7-ZD1-C6. The same power is supplied to the output switch VT1, which is controlled by this generator. To create favorable conditions for the operation of the key, a block on the VT2 transistor is installed in front of it, the task of which is to make the front and fall of the pulse sharper. The primary winding of the Tesla transformer TH1 is connected to the key output. A longitudinal wave is formed on its secondary high-voltage winding, which enters the power transmission line through the X3 connector (Line in Figure 3).

Capacitor C7 is not resonant and serves to limit the amplitude of oscillations when the receiver is turned off or its load is off. Capacitors C1 and C2 are used to protect the power supply from sudden voltage surges and at the same time create an artificial ground. They are required in this scheme.

Fig.2. Longitudinal wave receiver

Fig.3. Wiring diagram for transmitter, transmission line and receiver

The receiver is shown in Figure 2. It consists of a modified Avremenko VD2-VD5 plug, a metal body (cap) and an EL1 LED lamp. One input of this plug is connected to the transmission line through the X4 connector, and the second is connected to the metal body of the receiver, which at the same time serves as a secluded container.

The connection diagram of the transmitter, communication line and receiver is shown in Figure 3.

In this circuit, a high-voltage mosfet transistor FCA22N60N is well suited as an output switch VT1. You can choose another similar one, with a high rate of voltage rise, at least 25 V/ns. The transistor must be installed on a small radiator.

List of other elements of the circuit:

• PS1 - power supply unit (module) 220-12 V and 2 A, for example like this ;
• DG1 - two-phase generator, microcircuit TL494 ;
• VT2 - p-n-p transistor S8550 ;
• VD1 and VD2-VD5 bridge - diodes UF4007 ;
• ZD1 - suppressor 1.5KE18CA ;
• C1, C2 - 1-1.5 kV film or ceramic capacitors, for example, such ;
• C7 - 650 V film capacitor;
• R7 - resistor for 2 W power dissipation;
• X1-X2 - power cord;
• X3-X4 - any connectors, for example such .

The secondary winding of the Tesla TH1 transformer is wound first on a cardboard frame from a kitchen foil 35 mm in diameter. In extreme cases, you can use a 40 mm plastic sewer pipe, but then the coil will give slightly worse results. The frame should be about 11 cm long, it can be longer, but then more ferrite rings will also be required. A copper wire in varnish insulation 0.25-0.3 mm is wound on this frame until it is completely filled, only 5 mm should be left at the edges to secure the wire. A core made of glued ferrite rings of 28x16x9 2000NM brand is inserted into the frame. Another standard size is also possible, the main thing is that they fit into the tube. For example, the diameter of 32 mm does not fit anymore. The permeability can be taken higher, for example 3000 nm. The authors got 13 such rings. The inductance of such a coil is about 6-10 mH.

On top of the secondary, from one of the edges of the frame, 25 turns of wire with a diameter of 0.6-0.7 mm are wound. This will be the primary winding that connects to the key output at VT1.

The EL1 lamp should be an LED filament lamp, and have a power of 4W: example. This llama is also called the Edison lamp. With it, the device has a maximum efficiency approaching 100%. Some conventional LED bulbs are suitable, but not all manufacturers. With such lamps, the efficiency of the device is of less importance.

The location of the blocks (1-2) of the transmitter does not play any role. The third block (Fig. 1) contains a Tesla transformer TH1 - it is desirable to place it as far as possible from the first two. The variable resistor R6 should be placed as close as possible to the terminals of the DG1 microcircuit (Fig. 4), and even better - connect its case to the common wire of the circuit.

Fig.4. Assembling the longitudinal wave transmitter

Fig.5. Partially assembled working longitudinal wave receiver, near which the cat likes to sleep :)

A lamp holder and an X4 connector are attached to the receiver's metal housing. The connector must be well insulated from the case. The body itself houses the VD2-VD6 diode bridge, one end of which is fixed to the body (Fig. 5).

Fig.6. Assembled receiver and transmitter

Fig.7. Working device

To configure the device, it must be assembled. Trimmer resistor R2 should be in the middle position. Resistor R5 makes a rough adjustment of the resonant frequency of the master oscillator, which should correspond to the general resonance. This process is best controlled with an oscilloscope with the probe near X3. It is necessary to tune in to the maximum amplitude of the oscillations, and then check the fine tuning of the frequency with the variable resistance R6. The lamp on the receiver should be on.

The brightness, and, accordingly, the power on the lamp is adjusted by the resistor R2. It is recommended not to go too far from the middle position of this resistor.