Keywords: electromagnetic radiation detector
Electromagnetic radiation detector
As a variety of electrical appliances enter the family, people should not worry about being harmful to electromagnetic radiation, but the average person has not thought of self-made small devices, detecting whether the electromagnetic radiation will endanger you and your family. The electromagnetic radiation detector introduced here is extremely simple circuit design and the most common inexpensive components. Fans can do it yourself. 1. The principle is shown in Figure 1. The sensitive element used by the detector is a inductive coil (L1) connected to the field effect transistor (T1). T1 is polarized by a set of fixed resistance (R1) and variable resistance (Aj1) in its conductive zone. The drain of T1 will exhibit an enlarged electromotive force generated in L1. The amplified signals present on the resistor R2 end feet are sent to the second magnification on the common emitter set around the NPN transistor T2 via the capacitor C1. The amplitude of the signal presented on the collector of T2 is of course depends on the surrounding radiation intensity; if testing with an oscilloscope, a voltage waveform of 100 mV or more can be seen at the T2 collector. Capacitor C2 is a coupling capacitor, which transmits the signal after T2 to T3, and also acts as a DC.
The base of T3 is to establish a bias voltage by fixed resistors R5, R6, and variable resistor AJ2. Adjusting AJ2 allows T3 to reach a radiation cut-off point, thereby extinguishing the light-emitting diode D1 in the current electrode circuit. When the radiation reaches a certain strength, the negative half wave of the T2 output signal will turn on T3, thereby lighting the light emitting diode D1. The resistor R7 can limit the current through the light emitting diode D1. Since the detector is only used to determine the range of radiation pollution, a simple switch button (P1) is set. Capacitor C3 is used as a power source (BAT1) filtering. 2. Making Figure 2 is a printed circuit wiring diagram. Figure 3 is a component assembly diagram. Considering the entire circuit and battery to be installed in a plastic box. The size of the printed circuit cannot be too large, the pin can not stay too long, so as not to install or cover the cover. 3. After the debug is installed, first place the detector at a position away from the lighting line or a high voltage (eg, the center of the room). When the mounting direction of the transistor and the light emitting diode is checked, the AJ1 is rotated clockwise until the voltage reaches 9V, and the indicator lights up. Before adjusting, it is best to temporarily weld the button P1 with a soldering iron. Otherwise, you should hold it in the adjustment process. Adjust AJ2 in both direction in the opposite direction, the adjustment should start on the light-emitting diode light, terminate in the extinguishing state. Once the light emitting diode is extinguished, AJ2 has been adjusted in place. Don't adjust again. When adjusting AJ1. The detector should be close to (distance a few centimeters) radiation sources (such as wall embedded power socket, television, Hi-Fi equipment, etc.). In the case of rotating AJ1 counterclockwise, when the detector is adjacent to the radiation source, the longer the radiation source, the more it is easy to light, and the detector is gradually projected to the radiation source, moved to D1. The luminous position; then move the detector step by step, and moved to D1 no longer continuously luminescence. If the transistor T1 is continuously turned on, it indicates that the AJ1 has not been adjusted. Although AJ1 is not easy to be adjusted once, it can be adjusted in place with a few times. The detector can be tried after the AJL is adjusted. The trial results show that just leave the video device or the computer screen 1M or more. Leaving the electronic alarm of 40cm or more, leaving the bed headlight power cord 20 cm or more, will not be damaged by electromagnetic radiation. You will also find it. The ground metal shield has a strange radiation protection effect, and the outer radiation of the shielded device is close to zero. The detector also detects whether the switch on the socket plate or wiring board is turned off from the power cord. In short, you will discover its new use at any time.
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