Voltage Doublers

Author: J.B. Hoag

Fig. 11 E. Voltage doublers

Figure 11 E shows the principle of the voltage-doubler. Referring to (a), when the transformer secondary voltage is + at the left, the upper tube 1 conducts electricity into the condenser C₁. During the next half-cycle, the lower tube 2 fills condenser C₂ and C₁ is discharging through the load R. If R is not too small, both condensers become charged to nearly the peak supply voltage E. Since they are connected in series, with the polarity indicated, their total voltage, which is applied to the load, is 2E. Hence the name " voltage-doubler." The output voltage is indicated in (b) and is seen to be comparatively constant, the ripple amounting to approximately 5 per cent of 2E. When additional filtering circuits are added, the ripple will be only a small fraction of 1 per cent. The ripple frequency is twice the line frequency.

Figure 11 E (c) shows a doubler circuit which is often used without a transformer. The tube is called a double-diode rectifier.

The full-wave doubler circuit has been generalized to give 4E, 6E, etc., and is then used to produce very high voltages for atom-smashing experiments.