Grain pest alarm circuit

In the vast rural areas, state-owned grain depots and flour mills store a large amount of grain. In order to predict pests in time to avoid losses to the country and individuals, photoelectric control pest detection alarms
are designed .     Photoelectric control pest detection alarm is used to detect the occurrence and density of pests in grain warehouses . It has a high accuracy of prediction, has audible and visual alarms and counts and displays pests. In the detection state, the operating current of the whole machine is only about 2. 5mA, and it can be powered by three AAA batteries.     (1) Working principle of photoelectric control pest detection alarm as shown in the figure. Pests in granaries, especially larvae, have a habit of burrowing into holes and cracks. This habit is more obvious in the early stages of emergence. This alarm is designed based on this principle. It consists of a handle, a porous pipe, a probe and an alarm counting part. The alarm counting part is installed in the duty room, and the other parts are buried in the granary, and the two are connected through wires . The working procedure is: after the pests drill into the porous pipe, they enter the collection mattress and pass through the sensor channel. The photoelectric sensor located in the channel generates an electrical pulse. This pulse is output in two channels, and one channel triggers the thyristor and i/TH. When it is turned on, the buzzer HA connected in series with the thyristor VTH is energized and sounds an alarm. At the same time, the light-emitting diode VD1 connected in parallel with the alarm emits light to indicate the location of pest occurrence (this is very necessary for multi-bank and multi-probe detection). If the alarm cancel button S3 is not pressed, The alarm will sound continuously, reminding people to take measures promptly and accurately. After pressing the SB3 key, the alarm will stop immediately. The other channel triggers the counter to count. Every time an insect falls into the porous pipe, the counter will automatically count. After pressing the S3 key, the digital tube will light up and display, and the number of insects can be read. In order to save power, you should release the S2 key after reading. When you need to clear "0", just press S2.