情境
A white cane for visually impaired users detects obstacle contact with a normally-open pushbutton, activating a vibration motor for tactile feedback.
這張圖裡有什麼
看懂背後的決策。
01
Use a low-side NPN transistor (2N2222) to switch the vibration motor without overloading the pushbutton contacts.
02
Include a flyback diode across the motor to suppress inductive voltage spikes.
03
Add a pull-down resistor on the transistor base so the motor stays off when no obstacle is touched.
Battery-powered tactile alert devices that activate a small DC motor or buzzer from a momentary contact sensor.