SparkFun Forums

[mvizzion]

I'm working a project right now that requires switches to be triggered without actual physical contact. I'm thinking reed switches or hall-effect sensors are the way to go, but I'm a total beginner when it comes to electronics.

My goal is to have a few switches an inch or two part from each other that are triggered when a magnet gets within about 1/2" of it.

Ideally, they would only be triggered when the magnet is directly (or at least somewhat directly) above it, rather than beside it (so as to not trigger the other sensors by accident). That may or may not be realistic with these, but that's where I'm hoping your expertise can help.

Which should I use? Hall effect sensor (https://www.sparkfun.com/products/9312) or reed switch? (https://www.sparkfun.com/products/10601)

Thanks in advance,

Michael

[Mee_n_Mac]

For those distances I'd use Hall effect sensors though probably not the one SFE carries. If you read the comments at your link, it's a latching type. That is, once "tripped", it stays "tripped" until a magnet of reverse polarity is brought near it. Just taking the magnet away isn't enough to reset the sensor output. You can buy non-latching sensors in varying sensitivities from Mouser, Jameco, DigiKey, etc. Odd that SFE doesn't carry one.

As for multiple sensors, you can buy an IR sensor that, over the distance you mentioned, measures the distance and spits out a voltage indicating distance, that can be read by other circuitry to do your switching. Of course one of those is prolly more $$s than 3 Hall sensors.

[mvizzion]

Thank you - that is very helpful. I'll grab some from Mouser and see what I can do!