Using circuit diagram below can be built a voltage converter, able to convert a 70-260V AC to a 180-350V DC voltage.
For this, a rectifier contained in a MC34161 is used, as a voltage doubler for low input voltages and as rectifier for high standard input voltage.
A variation of four times of the input voltage is reflected in a variation of not more than two times in output voltage.
MC34161 has included a reference voltage source which supplies a voltage of 2.54 V to pin 1. The signal applied to pin 2 is compared with internal voltage of 1.27 V.
R2-R3 voltage divider provides change state of internal comparator which grow output input voltage over 135 V (pin 5 passes in 1 state). The potential at pin 2 is less than 1.27 V. Triac is blocked and disconnects median connection between the two output capacitors, C2 and C3, such that doubling output voltage can not be produced
When the input voltage is less than 135 V, pin 2 is maintained above the potential value of 1.27 V
Diodes D2 and D3 and capacitors C2 and C3 will function as voltage doubler.
Zener diode D5, together with R1 and C4, integrated circuit provides power to a stable source of 12 V. The time required passing standard rectifier circuit of the voltage doubler is determined by R4-C1.
Operating voltage of capacitors C2 and C3 must be> 250 V.