4W single wire power transmission. Optimal generator
A little earlier we presented you a rather interesting system of single-wire transmission of electrical energy at 4 watts. It used a fairly common generator on the TL494 microcircuit, which, with all its advantages, still required manual tuning of the resonant frequency. But this property is one of the main conditions for the appearance of the single-wire transmission effect. In addition, a relatively bulky Tesla transformer was used at the output. In this part of the work we will talk about a more optimized generator that automatically finds the resonant frequency and can work with almost any high-voltage transformer. The generator circuit can be powered from a voltage of 12 to 32 Volts, contains relatively few parts, has a high efficiency and turns out to be quite reliable in operation. It can be used both in single-wire systems and by itself, for example, to generate high voltage or spark discharges.
The generator circuitry was borrowed from this work, with some simplifications and improvements. For example, it turned out that devices with low output currents do not require a current transformer and protection system, which greatly simplified the entire circuit (Fig. 1). It works the same way: the DA1 half-bridge driver is held in an unstable state using the R5C3VT1 negative feedback chain, meanwhile, positive feedback is created by the R4R7C4 chain, which creates conditions for self-excitation of the circuit. The resonant frequency is found from the condition of the capacitance C6 and the inductance of the winding of the high-voltage transformer TH1.
The generator circuit is presented separately here, since it has interesting properties on its own. It can operate, in principle, with any high voltage transformer at the resonant frequency, thus providing the best possible conditions for the high output voltage and overall efficiency of the device. For example, with TVS transformers, the circuit gives the longest streamer length. At the same time, unlike the circuit on the blocking generator, the output transistors do not heat up, and the generator automatically selects the mode, depending on the load (spark). For fuel assemblies, the primary winding is wound on a free core and contains 25-30 turns of wire, or there is a similar winding from among those already available.
If the generator circuit is powered from a voltage of 12-15 V, then the DA2 voltage stabilizer can be omitted, and its "IN" and "OUT" pins can simply be connected with a jumper on the board.
Generator Element Base
Any high-voltage transformer that can give 5 kV and higher on its secondary winding is suitable as TH1. A good option turned out to be next transformer.
List of other elements of the circuit. Valid substitutions are given in parentheses:
- DA1 - half-bridge driver: IR2104 (IR2109);
- DA2 - 12 volt voltage regulator L7812;
- VT1-VT2 - mosfet transistors IRF3205;
- VT3 - n-p-n transistor S8050;
- VD1-VD3 - diodes UF4007;
- ZD1 - unidirectional suppressor 1.5KE12A;
- C4, C6, C7 - polypropylene (film) capacitors with an operating voltage of 250-400V;
Single-wire system connection diagram
The generator used here also simplifies the general scheme of a single-wire power transmission system (Fig. 2). The 12-32 V voltage is supplied from the PS1 power supply unit to the GG1 generator, and from it to the single-wire line. The receiver is exactly the same as the one used in the previous part of this work.
Capacitors Cp1-Cp2 must be rated for a voltage of at least 400V, and their capacity can range from 250 to 1000 pF.
Setting up and editing
The generator circuit starts working immediately, without any settings. This can be controlled by an oscilloscope, the probe of which must be located near the XS4 pin (under no circumstances connect the probe directly to this connector). If the trimmer resistor R7 is brought to the position of the minimum resistance, then the oscilloscope should show continuous sinusoidal oscillations with a frequency of 10-40 kHz (depending on the primary winding of TH1). But by adjusting this resistance, it is possible to achieve the appearance of bursts of pulses. This is a very interesting and economical mode of single-wire power transmission that remains to be investigated.
Since there are few details in the transmitter circuit, and the transistors do not require radiators, the printed circuit board, together with the high-voltage transformer, turns out to be quite compact 51 * 61 mm (see below).
Reliable partner for PCB production
Industrial version: PCB (open)
The industrial version provides a set of documentation for the industrial production of the board: GERBER file for the production of a printed circuit board, BOM file of the specification of components and a schematic diagram showing the values of the elements. All this allows you to immediately order a PCB, for example, here, and then quickly assemble it.