Powerful transformerless voltage converter, 5-15/10-30 volts 2 amperes. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Voltage converters, rectifiers, inverters
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On fig. 4.11 shows a voltage doubler circuit capable of providing a current of up to 2 A in the load. The converter is based on a pulse generator on a logic element DD1.1, covered by a feedback circuit R1, C1, R2, which sets the generation frequency. The pulse signals generated by the generator in antiphase are fed to the inputs of the logic elements DD1.3 and DD1.4, which control powerful key transistors VT1 and VT2.
To eliminate the possibility of a short circuit of the power source during their switching to the second inputs of the elements DD1.3 (through the inverter DD1.2) and DD1.4, pulses are received that are delayed by about a quarter of the period by the integrating circuit R3, C2. Due to this, the opening pulses (of negative polarity relative to the emitters) on the bases of the transistors are separated in time, and the through current through both transistors is excluded. If the transistor VT2 is open, the capacitor C3 is charged through the diode VD1 to the power supply voltage.
After half a period, transistor VT1 opens, capacitor C3 is connected in series with the source, and capacitor C4 is charged through diode VD2 to almost double the supply voltage. IC CD4093 can be replaced by K561TL1. Transistors should be used from the KT825 series and diodes from the KD212 series. To reduce the level of ripples at maximum load currents, it is desirable to increase the capacitance of capacitors C3 and C4 to 10 μF and, in addition, connect a film or ceramic film with a capacity of 4 ... 0,1 μF in parallel with capacitor C1.
Author: Semyan A.P.
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