Relay: Relay is the behavioral generator in decoder, normally decoder can match 9 relay, have 5 bigger relay among them, the fluctuation that is control cloud stage controls a movement, the others 4 lesser relay are control aperture of 3 alterable camera lens, change times, focusing. Below the pine, the relay such as ohm is top-ranking product, but the price is higher, use in the domain such as entrance guard controller normally. There are two brands in the relay that monitoring decoder uses more, song Le, collect harbor, quality difference is not big, the relay in be being used actually fault rate is not high, my individual thinks basic negligible not plan. But when decoder works, relay should leave often close, and leave every time there is an instantaneous electric current to pass when closing. If relay the size is too small, instantaneous electric current exceeds the capacity of relay likely, the service life of relay can shorten greatly, must use 7A above the relay of rated job electric current, and some manufacturer too the small relay that seek cost and chooses 1A. Still a problem needs to notice, camera lens pilot cancelled when some decoder are designed 3 relay, replace with dynatron and resistor, fault rate of in use of this kind of design is not high also, it is basic in normal limits, but my individual holds reservation opinion, the drive ability of dynatron is limited, should use in relatively complex environment when, may not stabilize. Communication chip: The communication chip of decoder basically is responsible of signal of the data on 485 bus line receive, the most commonly used is 75176 chip, 75176 chip are opposite a kind of older product, but the value is inferior, stability is better, but poorer on drive ability, because decoder attributes bus line of RS485 one-way communication, issue of nonexistent drive capacity, to the market with intense now competition, the 75176 chip of low cost become 95 ％ above to produce the alternative of decoder manufacturer. But the proposal is not used use the 75176 code converter that regard communication as chip, because drive ability is limited, when controlling 32 above decoder to move, fault rate is very high. Defend thunder system: The decoder with better brand contains the simple and easy system that prevent thunder normally, basically be to prevent inductive thunder to be opposite through 485 bus line of decoder destroy. Price of the system that prevent thunder will be even higher than decoder itself severalfold, design the relatively simple and easy system that prevent thunder normally so. With Shenyang the Xian Ke decoder of limited company of electron stalking or branch is Xian Kaili exemple, the part that prevent thunder should prevent thunder diode to finish by 2, can destroy in order to prevent the inductive thunder of 10 millisecond 600W, basically can resist common response thunder makes a surprise attack. Exceed the diode that prevent thunder bear when inductive thunder energy when the limit, prevent Lei Er pole to be in charge of meeting burn down, draw inductive thunder energy at the same time, parts of an apparatus of protective decoder interior and power source transformer are not destroyed. Prevent detonator by burn down hind, after will preventing detonator to get off, decoder can work normally, but had not had the function that prevent thunder. Because decoder use environment is complex, often be produced by circumstance of be struck by lightning, when the proposal chooses decoder, the choice contains the product of the system that prevent thunder.
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