The power supply with adjustable voltage, 220/0-20 volts 0.4 amps
For several years I use two PSUs, which are used in sources consulted during the examination and establishment of various designs. Gathered them according to the descriptions in Amateur literature.
The first power unit (Fig. 1) - the most simple, it allows you to get the output (at the terminals x2, XS) DC voltage in the range from almost zero to 20 In at load currents up to 0.4 A. One of its main parts - the transformer T1 is may be, for example, television output transformer frame scanning TCE-LM. Its winding I - high resistance (pins 1,2), (II - low impedance (pins 3,4,5). Will also fit any other transformer, providing the voltage on the secondary winding 18...20 V At a load current of 0.5 A.
The second block (Fig. 2) is slightly more complicated, but allows you to supply the load current up to 1 A. in addition, the output voltage it is possible to control the voltmeter scale PV1 15 V.
Step-down transformer T1 is hand made. It will need a W-shaped the magnetic core cross section of about 5 cm2. Winding I must contain 1380 turns the PEV-1 0,12, winding II -135 turns sew-1 0,55. You can also use and the finished transformer to deliver on the secondary winding voltage 15... 18 In load current of about 1.5 A.
To power transistors (PA and CTA) do not overheat, they must set on a commercially available finned heat sinks or make yourself from the aluminum plate with a thickness of 2...3 mm and a size of approximately 100x100 mm.
Author: V. Dokukin