This video provides an in-depth examination of a surprisingly large magnetic reed switch, exploring its construction and electrical characteristics. After visually demonstrating its contact mechanism under a microscope, the presenter tests its current handling capabilities and switching behavior using a 1-ohm load and an oscilloscope. The primary finding is the significant voltage ringing (spikes up to 12V) observed on the output whenever the switch contacts open or close, despite its otherwise fast switching edge. The video highlights this inductive ringing as a critical consideration for circuit designers, especially those seeking clean, fast transitions. The switch's impressive current rating (stated 6A, tested to 1.7A) and a distinctive audible click are also noted.
What's on the Bench? A Deep Dive into a Large Reed Switch
0:00:08 The presenter introduces a large magnetic reed switch found in a store, noting its function to close electrical contacts when a magnet is nearby.
0:00:31 A microscopic view of the switch's internal contacts reveals their polished appearance and precise operation as they open and close.
0:00:48 The switch's packaging indicates a rating of 100 watts and 6 amps, prompting the presenter to test its performance.
0:01:09 For testing, a 3D-printed plastic clamp is used to securely hold the non-magnetic switch, preventing interference with the activating magnet.
0:01:51 The switch is wired with a 1-ohm load and a power supply set to 1 volt, resulting in a current of approximately 849 milliamps when the switch is closed.
0:02:48 Using an oscilloscope, the voltage across the load is monitored, revealing substantial "ringing" (oscillations) when the switch opens or closes, with peak voltages reaching up to 12 volts.
0:05:36Key Takeaway: The video demonstrates that while magnetic reed switches provide a fast switching edge, their inductive nature can generate significant voltage ringing, which is an important consideration for circuit design, especially when clean signal transitions are required.
0:05:51 Further analysis of the oscilloscope trace shows a fast rise time for the switching edge, though its measured speed might be influenced by the power supply's response rate.
0:07:43 The switch successfully handles the tested currents (up to 1.7 amps) without issue, suggesting its stated 6-amp rating is plausible.
0:07:59 The video concludes by highlighting the notably large size of this particular reed switch and its distinct, satisfying audible "click" when actuated.