How do are the alarm sensors powered?

[admin]

Most popular alarm sensors include motion detector, door contact, smoke detector and so on.

For powering,

1) For wireless alarm, mostly using batteries, the kind of batteries depends on different models e.g. AA, AAA, 123A, etc. Battery life will be affected by usage and the power consumption of the sensors, length probably with a scale between half to 1 year.
2) For wired alarm, mostly requires 9-12V DC power supply.

Some big consumption sensors (no matter wired or wireless) require DC power supply, these may include outdoor motion detector, gas leakage detector.