Rain and snow falling amount remote sensing circuit composed of LM7805 and 89C2051

In order to estimate the water situation in winter, it is necessary to measure not only the rainfall but also the snowfall. Based on the original rainfall telemetry circuit, this circuit can realize the dual function of measuring the rainfall and snowfall by adding some components, as shown in the figure. When it rains, rainwater flows into the bucket FD below through the funnel LD of the rain gauge in Figure (a). When one side of the bucket collects just 1mm of rainfall, the bucket loses balance and flips, and the rainwater in the bucket is also discharged. At the same time, the other side of the bucket begins to collect rainwater. When it rains continuously, the bucket keeps flipping left and right. In the signal conversion circuit of Figure (a), the middle rod of the bucket has a magnet. When the bucket flips left and right, the reed switch (1) and the reed switch (2) are alternately closed and disconnected, sending signals to the terminal, and then the terminal transmits rainfall data to the central station through the carrier. To make this circuit, first add a hot air blower FJ in the rain gauge to blow the funnel directly. A wire mesh W is installed horizontally under the funnel mouth. The temperature switch H is installed 1m outside the rain gauge, and the circuit board is placed in the rain gauge. The rain and snow falling amount telemetry circuit is shown in Figure (b). IC3 is a single-chip microcomputer 89C2051, its P3.1 terminal is the temperature detection port, P3.2 terminal is the snow water detection port, and P1.1 terminal is the fan working condition control port. Since the temperature switch H contact is set at the 0℃ scale, when the temperature is higher than 0℃, the transistor VT1 is turned on, the relay works, its normally closed contact J1-1 is disconnected, the optocoupler IC1 is not connected, and IC3 stops detecting due to the setting of P3.1. When the temperature is lower than 0℃, the transistor VTl is disconnected, J1 does not work, J1-1 is connected, the optocoupler ICl is turned on, the P3.1 terminal is at a low potential, and IC3 starts to detect whether it is snowing. At the same time, P1.1 is at a low potential, the optocoupler IC4 is turned on, the relay J2 works, its normally open contact J2-1 is closed, and the hot air blower works. If there is no snow on the rain gauge funnel (i.e. no snowfall occurs), P3.2 is set, the hot air blower stops working for 5 minutes, and starts working again after 4 hours, and repeats this process. If it starts to snow, the funnel heated by the hot air blower melts the snow. If a drop of snow water flows through the wire mesh W once, W is turned on to turn on the transistor VT2, and then the optocoupler IC2 is turned on, P3.2 presents a low potential once, and the hot air blower works for 5 minutes. When continuous water droplets flow through W, P3.2 continues to present a low potential, and the hot air blower works continuously until no more water droplets flow through W. The program flow chart is shown in Figure (c). If there is snowfall within 4 hours when the hot air blower is not working, according to the local annual snowfall, the rain gauge will not be filled with snow, so there will be no error, but there will be a delay in the snowfall measurement. A certain time delay will not have much impact on the measurement of snowfall. After winter, Sl can be manually disconnected to stop the snow measurement function.