Efficient way of driving latching relays

If you need to keep relay turned on or off for a long time, then standard relays may not be best solution. First of all in order to keep relay switched, power must be applied. If you are using mechanical relay, then coil must be constantly energized. This way relay draws power and for battery operated equipment this is not acceptable. SSR relays might be a better solution, but signal still need to be applied in order to keep it turned on. In such cases there are latching relays used. These relays keep their state after switched and power is removed. They are common where relay need to be on or off for long time. Controlling such relays is a bit trickier than regular ones. First of all relay can… Continue reading