情境
Designing a simple water level controller using an NPN transistor as a switch to drive a pump motor, with a high-level probe to detect water level.
這張圖裡有什麼
看懂背後的決策。
01
Using an NPN transistor (Q1) as a switch instead of a relay for simplicity and low cost.
02
A pull-up resistor (R1) keeps the transistor on when water drops below the high probe.
03
A second resistor (R2) limits current when the probe is submerged, protecting the transistor base.
04
A flyback diode (D1) protects against voltage spikes from the pump motor.
05Two probe terminals
common grounded probe and high-level sense probe.
Suitable for automatic water tank filling in residential or agricultural settings where a low-cost, reliable electronic control is needed without complex logic.