The construction of the relay module: as shown, A is an electromagnet, B is an armature, C is a spring, D is a moving contact, and E is a static contact. The working circuit of the electromagnetic relay can be divided into a low voltage control circuit and a high voltage working circuit. The control circuit is composed of an electromagnet A, an armature B, a low-voltage power source E1 and a switch; the working circuit is composed of a small bulb L, a power source E2, and a static contact and a movable contact corresponding to the switch. Connect the working circuit. In the normal state, D and E are not connected, and the working circuit is disconnected. When the movable contact is pressed with a finger, the working circuit is turned on due to the contact between the D and E moving contact and the static contact, and the small bulb L emits light. When the switch S is closed, the armature is sucked down by the electromagnet, and the movable contact is in contact with the two static contacts at the same time, so that D and E are connected. At this time, the spring is elongated, and it is observed that the working circuit is turned on, and the small bulb L is illuminated. When the switch S is turned off, the electromagnet loses its magnetism and is unattractive to the armature. The armature returns to the original position under the tension of the spring, the movable contact is separated from the static contact, the working circuit is cut, and the small bulb L does not emit light.

Temperature automatic alarm relay: When the temperature rises to a certain value, the mercury surface of the mercury thermometer rises to the wire, and the mercury is the conductor. Therefore, the electromagnet circuit is turned on, the electromagnet attracts the spring piece, the electric bell circuit is closed, and the electric bell sounds an alarm. When the temperature drops, the mercury surface leaves the wire, the electromagnet circuit is disconnected, the spring piece returns to the original state, and the bell circuit is disconnected. The bell no longer sounds.

Alarm relay module principle

Working principle: When the electromagnet is energized, the armature is sucked down to make D and E contact, and the working circuit is closed. When the electromagnet is de-energized, it loses its magnetism, and the spring pulls the armature and cuts off the working circuit. An electromagnetic relay is a switch that uses an electromagnet to control the on and off of a working circuit. The advantages of using electromagnetic relay control circuit: control high voltage with low voltage; remote control; automatic control. Anti-message alarm: K is a contact switch, B is a funnel-shaped bamboo cylinder with a float A inside. When the water level rises above the warning line, the float A rises, the control circuit is turned on, and the electromagnet sucks the armature. Then the alarm indicator circuit is turned on and the light is on.