Circuit Wiring Solution: DC Voltage Doubler Circuit Explained

Friday, September 26, 2014

The inverters, N3. . . N6, are connected in parallel and operate as a buffer stage to reduce the load- dependence of the circuit.
Depending on the clock signal of the oscillator, point A in figure 1a is connected to the earth rail for a particular time per period and to the supply voltage for a particular time.
This causes the voltage across capacitor C2 to rise to almost twice the supply voltage. If D1 is connected to earth and the -polarities of diodes D1, D2 and capacitors C1, C2 (figure 1b) are reversed, the output at A will be a negative voltage and, in the no load condition, it will be at the same level as the supply voltage.
In both cases, unfortunately, the output voltage is dependent upon the load. As the load increases, the output voltage drops; in contrast, the superimposed a.c. level rises. The table shows the values measured in the circuit for load currents of 5 mA and 15mA.
This simple circuit can produce a d.c. voltage which is approximately twice the supply voltage, in the no- load condition.
Whilst point A is connected to earth, capacitors C1 and C2 charge up to the supply voltage via diodes D1 and D2. The oscillator then switches point A to the supply voltage potential during the remaining period, capacitor C1 transfers a part of its charge to capacitor C2.
The 4049 IC contains a total of six inverters. Two of them, N1 and N2, form an oscillator together with R1 and C3, of which the frequency is about 10 kHz.