Reed Switch Current Limitation

Other Hardware General Electronics
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Hello everyone. Thank you for taking the time to read this post.

I am currently creating a circuit with a reed switch and a servo. However, I need some guidance regarding the selection of a reed switch.

I am using the standard DS2318 20KG Servo (off of Amazon). At stall current on the higher end, the servo draws 2.2A @ 6.8V. I need to route this power through a reed switch. I was wondering if a Reed Switch like this, could be used.

It has a sufficient carry current (2.5A), but the switching current is only 500 mA. If it makes a difference, I do not mind having to replace these switches when they became faulty.

Any and all advice is greatly appreciated. Thank you very much. I look forward to hearing from you all.

-Dawn

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Do you know why the switching current is so low? What happens when switch contacts produce an arc?

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  • Highly recommend you use a MOSFET, example AO4419
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IMG_6849
IMG_68494009×2272 1.82 MB

I've attached an image of the planned circuit - it's a little messy.

Paul, I am not actually sure why that switching current is so low but I would sure love to know.

An alternative circuit would be to drive the base of a transistor (or MOSFET) using the output of the reed switch. However, simpler is always better, which is why I want to use the simpler circuit (from the image), if possible.

-Dawn

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I'll ask again . What happens when switch contacts arc? Even in the vacuum of the reed switch, the contacts are eroded away or are welded together, or both. Either means a replacement of your reed switch.

Transistor Minimum Base Input
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  • No, that’s just a phrase. :roll_eyes:

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  • Add other Servo power control as needed.
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That makes sense, it would be a whole lot easier to use a transistor or MOSFET. If I used a circuit as shown in the picture, would it be functional?

IMG_6850.HEIC
IMG_6850.HEIC3024×4032 2.31 MB

Any particular improvements in mind? In addition, would it be possible for me to use a transistor with a higher rating, as opposed to a MOSFET?

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  • You should use HIGH side switching. (PNP)

  • MOSFETs are far superior.

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