Stabilized power supply, 220/0-27 volts 0,5 amps. Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Stabilized power supply, 220/0-27 volts 0,5 amps. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Power Supplies

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To establish and test various devices assembled on microcircuits and transistors, a power source with a wide range of output voltage regulation is required at significantly changing load currents.

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The main parameters:

Mains voltage, V.......220±15%
Stabilization factor......100
Output voltage regulation limits, V.......0...27
Load current, A ....... 0,5
Double amplitude of ripple voltages, mV.......1,0
Output impedance, Ohm.......0,05
Maximum load current, A ....... 0,6
This power supply is equipped with overload protection.

The output voltage is stabilized. As a transformer T1, a converted vertical scan transformer from the Start-3 TV was used. The secondary winding is removed, and another is wound in its place. Sections IIa and IIg each contain 215 turns of PEV-2 wire - 0,38, and IIb and IIc - 200 turns of the same wire each. Winding III consists of 28 turns of PEV-2 wire - 0,31. Transformer T1 can be made independently. W-shaped magnetic circuit with a cross section of the middle rod 4 cm2 (W 20 X 20). The primary winding consists of 2600 turns of PEV-2 wire - 0,16. The data of the remaining windings can be left unchanged.

The variable resistor R10 must have a dissipation power of at least 1 W (SPO-1). The reed switch K1 is made on the reed switch KM-2, its coil is wound with wire PEV-2 - 0,51 in one layer on a paper sleeve with a diameter of 4 and a length of 21 mm. Lamp H1 - type MH14 (2,5 V; 0,16 A) serves as an overload indicator. The reed relay, the HI lamp and the winding III of the T1 transformer can be omitted if, instead of the V8 zener diode, the AL307 LED with any letter index is turned on. The resistance of the resistor R2 in this case should be equal to 2,2 ohms. The glow of the LED will indicate an overload of the stabilizer.

Transistors V10 and V11 must have a static current transfer coefficient h21e > 50. Transistor V9 should be installed on a radiator with an area of at least 300 cm2.

The establishment of the stabilizer begins with the fact that instead of the resistor R11, a variable resistor with a resistance of 1 kOhm is turned on and its engine is set to maximum resistance. The slider of the resistor R10 must be in the lower (according to the diagram) position. The stabilizer is turned on and, by rotating the slider of the variable resistor installed instead of the resistor R11 *, the output voltage is set to 27 V. After that, the resistance of the active part of the variable resistor is measured and instead of it, the resistor R11 * is turned on with a constant resistance equal to the measured one.

Next, the resistance of the resistor R2 is selected, connecting to the output instead of the load a DC ammeter with a scale of 1 A. Unwinding the turns of the wire of the resistor R2, set the current to 0,6 A on the ammeter. Resistor R6 * is selected so that in the upper position of the resistor R10 the output voltage was zero. By selecting the number of turns of the winding of the reed relay K1 and moving the reed switch inside the coil, the required operating current of this relay is set. The output impedance is estimated by measuring the difference between the open circuit voltage and the voltage at maximum load.

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