DIODE CIRCUITS 



It sometimes happens that high direct voltages are derived from generators 

 whose output is pulsatory and uni-directional rather than sinusoidal and 

 alternating, and in this case voltage multipliers take a rather different form. 

 There is no difficulty in seeing, in Figure 6.28, that if the generator output 



J~[ 



FL 



-4 



\ 



Figure 6.28 



rises periodically to V and falls to zero again, then the capacitance will 

 charge to a voltage Kalso. Now, in Figure 6.29, add C^ and a high resistance. 

 Then between pulses Co will charge from Q so that the potential at B even- 

 tually reaches V also. When the next pulse arrives, A rises to V, carrying B 



V C. 



Figure 6.29 



Figure 6.30 



up to 2V, and if we provide another diode and a third capacitance we can 

 arrange for this capacitance to charge from Cg via the diode (Figure 6.30) so 

 that a smooth voltage 2K is available with respect to earth. This is the 



r-M^L — r 



Figure 6.31 



voltage multiplier for pulses and as in the Cockcroft- Walton circuit extra 

 voltage may be obtained by stacking further components on top. Thus a 

 pulse quadrupler is shown in Figure 6.31. 



108 



