情境
Two infrared beam break sensors are placed a known distance apart across a highway lane. A 555 timer measures the time between the first and second beam interruptions and lights an LED while the vehicle travels between them.
這張圖裡有什麼
看懂背後的決策。
01
Use two IR LED/photodiode pairs as start/stop sensors
02
Configure the 555 in monostable mode with the second sensor resetting the IC to stop timing
Reuse this netlist when you need a low-cost analog vehicle speed sensing front end, such as in highway monitoring, traffic counting, or speed warning displays.