Alarm With Reed Switch Or Magnetic Switch Electronics Circuits

The majority of home alarms use these switches on the doors. Normally consist of two elements, one with the sensor (reed switch), where the cables are connected and one containing a magnet inside. For optimal operation must observe the marks, that this case is arrows or triangles as in the example photo. Usually these switches are normally open, but to approach them the magnet is closed, then with closed doors are made as switches normally closed (NC). When installed make sure they are well close or pasting, and not activate if the door does not close accurate. If the door frame is steel or iron may be lost magnetic field and may need to place a large magnet.

The switch or sensor is a small glass bulb with two contacts that are attracted in the presence of (the magnet) magnetic field. The English name is reed switch and is better known than reed switch or reed switch. We can find them by typing "HYR-2001 Magnetic Reed switches Rhodium" down the page can see examples of where comseguir these switches if there is no shop electronics available There "reed switch" less common than 3 contacts: common, normally closed (NC) and normally open (NO) to alarm use the most common and are connected in series.

Q1 is a 2N2222A transistor, and Q2 is a 2N3906. You transistor 2N2222 and 2N3906 can utilize similar transistors taking precautions as to the pin connections and power, there is one very similar as the 2N3904 which is not suitable for being of little current 2N2222A 600mA, 2N3904 200mA.

When you can replace 2N3906 PNP transistor any small, because it should not bear much power the diodes (D1, D2) can be 1N4148, even as the 1N4001 rectifier diodes. C2 is 0.1 microfarad, its function is very high torque prevent the circuit is activated when connected the Led together with R6 are optional.

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