# Solenoid Lock with RFID sensor only working once

**URL:** <https://forum.arduino.cc/t/solenoid-lock-with-rfid-sensor-only-working-once/1102667>\
**Category:** General Guidance\
**Created:** [March 16, 2023, 9:20am UTC](https://forum.arduino.cc/t/solenoid-lock-with-rfid-sensor-only-working-once/1102667 "2023-03-16T09:20:25Z")\
**Posts on this page:** 1\
**Showing post:** 19

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**Author:** ![JohnLincoln](https://avatars.discourse-cdn.com/v4/letter/j/7ba0ec/32.png) [@JohnLincoln](https://forum.arduino.cc/u/JohnLincoln)\
**Post date:** [March 17, 2023, 7:28am UTC](https://forum.arduino.cc/t/solenoid-lock-with-rfid-sensor-only-working-once/1102667/19 "2023-03-17T07:28:48Z")

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Do you have a reverse biased diode connected across the solenoid coil?

The need for one is all explained in this pinned topic in the general electronics section:  
[Flyback diodes and why you need them](https://forum.arduino.cc/t/flyback-diodes-and-why-you-need-them/675409)

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