Relay (relay), also known as the relay is an electronic control device, which has a control system ( also known as the input circuit ) and the control system ( also known as the output circuit ) , usually used in automatic control circuit, it is actually with a small current to control a larger current "automatic switch ."

In the decoder, the operation of the relay is the generator . The decoder will usually match nine relay , which has five large relays, control PTZ movement up and down , and the remaining four smaller relay is to control three variable lens aperture, zoom, focus .

Panasonic, ohms relays are first-class products, but the price is higher , usually used in the field of access control and so on. Monitoring relays used in the decoder has a brand with more than that Zhejiang Harbour , in actual use relay failure rate is not high , I think basically negligible .

But the work of the decoder , the relay to the frequent opening and closing , and each has an instantaneous current open timely pass. If the relay capacity is too small , the instantaneous current may exceed the capacity of the relay , the relay will greatly shorten the life , be sure to use 7a above the rated operating current relay , but some manufacturers choose 1a relay too small to pursue cost.

Another issue to note the abolition of the three relay lens control some decoder design, instead of using transistors and resistors , this design is not in use, the failure rate is high, basically within the normal range, but I personally hold reservations, transistor drive capability is limited, when used in relatively complex environments, it may be unstable.