This article describes the use of wireless alarms alarm feedback principle, consists of two parts: the first part of the invasion by the anti-theft alarm detectors and micro-transmitter wireless components; second part of the wireless alarm receiver controller. The first part will be installed when used in the storage room, garage and other places need to guard against; the second part placed in the residents living room.
a, intrusion detectors and alarm transmitter part of the micro-
Second, the wireless receiver alarm control
Figure 2 is a wireless receiver alarm control circuit schematic diagram, which consists of super-regenerative receiver, amplification, shaping, signal decoding circuit and alarm circuit and other components.
In order to prevent occurrence of leakage power failure alarm, wireless alarm receiver controller uses AC and DC power supply in two ways, and automatic conversion. When AC power, the rectifier output of the 9V power supply added to the negative terminal of the diode D5, diode D5 closing the circuit to rely on AC power supply. Once the AC power failure, D5 loss of the negative side of the turn-on voltage 9V, 9V battery power to the circuit through D5 to achieve the AC and DC power supply automatic switching.
Figure 1, the small magnet and reed E finished products can be purchased in the market, the normally closed doors and windows alert sensors. Places required to prevent the gap between door and door frames are smaller, the door closed to solid, or by the wind may cause false alarms. L2 can be used or 1.5mm silver wire surrounded the enameled wire can also be directly printed circuit board. Encoder does not require coding switch, as long as the power of a point and connected to the positive or negative. Laminated with a 15V battery power. The transmission circuit can be made in a matchbox, smaller than the circuit board.
Figure 2, the alarm signal receiving and alarm control section, T1, T2’sß value requires no more than 100. L1 4.7µH inductor with a color code inductance, L2 with 0.5mm enameled wire in 4mm drill bit around the 3 turns on the self, the antenna can be used instead of soft wire 30cm long, K2 lift switch for the alarm, should be regular contact Open button. 9V laminated battery cell. In addition to the circuit power switch, alarm lift switch, power light, alarm lights installed in the panel, the other components are installed in a circuit board production.
According to Figure 1, Figure 2 selected components, soldered circuit board, the VD5026 and VD5027’s address set the same code and state code, check the correct power immediately after commissioning.
The alarm circuit is simple, the machine costs only tens of dollars. By changing the sensor transmitter and set VD5026/5027 the address code, the status code can greatly expand the use of the alarm (such as multiple alarms, data transmission, etc.).
test Comments: The entire circuit design more complete, simple structure, according to the author of the circuit, take the R1, R15 to 240kO, SCR take CR100-6, to complete the circuit production, the use of the oscilloscope transferred through the circuit, the effect can be achieved on paper above. The downside is that the machine interference and distance to be improved, when there is interference and obstacles, the effect is significantly reduced.
The working principle of this circuit and design method can be used as reference for the radio enthusiasts.