This source can be used to power any load capacity of up to 15 to 20 watts and has a smaller size than similar, but with a decreasing transformer operating on the frequency of 50 Hz. The power source is performed according to the scheme of a single-pulse high-frequency transducer (Fig. 5.32).
Transistor assembled oscillator operating at a frequency of 20...40 kHz (depends on settings). Frequency is adjusted capacitance C5. Elements VD5, VD6 and C6 form a chain running the oscillator. In the secondary circuit after the bridge rectifier is normal the linear regulator on the chip that allows you to have a fixed output voltage, regardless of variations in the input line voltage (187 242...In).
A pulse transformer is performed on the ferrite core M2500NMS or M2000NM9 size 1115x5. Winding wire made PEL-2. Winding 1-2 contains 600 turns of wire of 0.1 mm diameter and winding 3-4 contains 44 turns 0.25 mm diameter winding 5-6 - 10 turns of the same wire as the primary the winding.
If necessary the secondary windings may be several ( shown is only one), and for operation of the oscillator must be observed the polarity of the phase windings 5-6 in accordance with the scheme. Setting Converter is to obtain a stable excitation oscillator when the input voltage from 187 to 242 V. elements requiring the selection, marked with an asterisk. The resistor R2 may have a value of 150...300 ohms, and the capacitor C5 - 6800...15000 pF.
To reduce the size of the inverter in case of smaller withdrawn in the secondary circuit power ratings electrolytic filter capacitors (C3, C1 and C8) can be reduced.
Author: A. P. Seman