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Question about Hall switches that I am planning to use as limit switches.

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Posted by: @ronbentley1

@inst-tech et al 

An interesting post that got me thinking about these components as switches. Your link shows that there are quite a range of contactless switches svailable, so I suppose my query is general to all of these, although specifically to the cheap Hall effect switches readily available.

My query is this: do these switches suffer from 'bounce'? That is  do the need to be denounced when integrated into a mcu design?

Just wondering....


Ron B

@ronbentley1, Good question Ron, but no, since they are essentially contact-less, that eliminates the "bounce" that is caused by physical contacts. I guess one way of visualizing it would be to consider the contacts on a physical switch as leaf-springs, so when depressed and released, they tend to vibrate which causes the multiple contact you most likely encounter. The solid state has no contacts..hence, no bounce. Another feature of solid state over physical switches is no contact arc..That is the reason why with high voltage, that modern circuit breaker controllers use vacuum breakers to suppress the arcing that happen when the contacts open.

While this is off topic, I have provided a link to show what vacuum breakers are:

so you can can understand why this is important. For our discussion, there are many ways to eliminate contact bounce, and solid state is the way to go. programming in de-bounce routines work on very low voltage-current application, but will not protect the physical switch from arc flashing..remember in the old days before electronic ignition in cars & trucks, when we had points & condenser?  that was the job of the condenser ( ie: a capacitor) to suppress the arc when the contacts opened. Hope this helps with your understanding of how this all works..






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@ronbentley1 In this application bounce is not a concern, it's use is that of emergency stop, so any 'make' is sufficient. IOW, we would rather stop when not needed than not stop when needed.

First computer 1959. Retired from my own computer company 2004.
Hardware - Expert in 1401, and 360, fairly knowledge in PC plus numerous MPU's and MCU's
Major Languages - Machine language, 360 Macro Assembler, Intel Assembler, PL/I and PL1, Pascal, Basic, C plus numerous job control and scripting languages.
My personal scorecard is now 1 PC hardware fix (circa 1982), 1 open source fix (at age 82), and 2 zero day bugs in a major OS.

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ron bentley
Joined: 2 years ago
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Thanks Louis, that is most helpful and comprehensive.


Ron B

Ron Bentley
Creativity is an input to innovation and change is the output from innovation. Braden Kelley
A computer is a machine for constructing mappings from input to output. Michael Kirby
Through great input you get great output. RZA
Gauss is great but Euler rocks!!

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