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# System prepended metadata

title: 為何 Relay 的 coil 要加上 Flyback diode?
tags: [教學]

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# 為何 Relay 的 coil 要加上 Flyback diode?
Author: 家答
- [Inductive Flyback and Flyback Diodes](https://digilent.com/reference/learn/fundamentals/electronic-components/flyback-diodes/start)
- [How to choose a flyback diode for a relay?](https://electronics.stackexchange.com/questions/110574/how-to-choose-a-flyback-diode-for-a-relay)
[Diode package selection in flyback circuit for a relay](https://electronics.stackexchange.com/questions/404771/diode-package-selection-in-flyback-circuit-for-a-relay)
![image](https://hackmd.io/_uploads/rkbXUN-1lx.png)

### 沒加 flyback diode
Maximum Inductive Kickback: 5.4kV
![image](https://hackmd.io/_uploads/rJRZDmWyxe.png)
![image](https://hackmd.io/_uploads/B1oHvmZkel.png)

### 有加 flyback diode
Maximum Inductive Kickback: 743mV (D1 的順向偏壓)
![image](https://hackmd.io/_uploads/Sk7kP7Wkxx.png)
