The use of chip CREA (B) and standardized transformer TP-220-50 allows you to produce a simple and reliable source power for various appliances.
Output voltage can be adjusted steplessly in the range from 2 to 12 V. the Maximum load current of 1 A, the amplitude of the ripple the output voltage does not exceed 2 mV.
Fig. 5.3
Electric circuit device shown in Fig. 5.3. The unit is assembled according to the standard scheme consistent compensatory stabilizer voltage. In order for the chip DA1 not to dissipate too much heat the power provided in the stabilizer discrete switching terminals of the secondary windings of the transformer section S2.1 switch. At the same time switch and resistors R4...R7 feedback dividers for installation adjustment limit the output voltage. On each of the subbands desired voltage can be set variable resistor R3. The switch provides the setting ranges of the output stress 2...5, 5...7, 7...9, 9...12 V.
DA1 chip has an internal overload protection. The operation of the source is led HL1.
For ease of use scheme can be supplemented pointer voltmeter.
The design of the power source transformer can to replace the more powerful from the same series: TP-220-50, TP-220-50, TP-220-50 (pin numbering connect the windings does not change, but will increase the size and the weight of the device).
The chip is designed to work with heat sink, and it should be fixed on the radiator, wherein the radiator does not need to be electrically contact with the hull design.
For ease of setting the boundaries of the ranges of the output voltage trimming resistors R4...R7 is better to use multi-turn, for example type SP5-2 or SP5-14. Capacitors are used: C1, NW type K50-29; C2.C4-K73-17.
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