Use low operating voltage relays for mains circuits b

If a low operating voltage DC relay is used in commercial power, it needs to be reduced by a step-down transformer and then rectified before it can be used, but
this is costly. For this purpose, a resistor or capacitor step-down circuit can be used , as shown in Figure 6 4.
    Figure 6-4 (a) shows the resistor R step-down circuit, the diode VD half-wave rectification, and the capacitor C filter and voltage stabilizing circuit; Figure 6-4 (b)
shows the resistor R step-down circuit, diode bridge rectifier vc, and capacitor C filter and voltage stabilization circuit. circuit. The voltage applied to the relay KA coil by this circuit is more stable than Figure 6-4 (a). The disadvantage of Figure 6-4 (a) and Figure 6-4 (b) is that the power consumed in the resistor R is large. Figure 6-4 (d) shows the best performance among the four circuits .