Coin sized magnet detector

Community Projects
1

I’m looking to build a vibrating magnet detector around the size of a watch face if possible. I have a neat idea but this would need to be made before the idea takes off.

So (keep in mind I’m new to this)

List of things needed:

Cell Battery (3v) 20mm https://www.sparkfun.com/products/338

Reed switch (insulated): https://www.sparkfun.com/products/10601

Vibration motor: https://www.sparkfun.com/products/8449

Beyond that I’m really not sure what I need to do to house the unit effectively or how to attach everything nicely.

The idea is to keep this very small and functional, I’m trying to keep it between a quarter and the standard watch face for size.

Thank you anyone for help in advance. This forum is really awesome, TONS of information logged in here :smiley:

2

What do you mean by “magnet detector”?

3

Basically when the small unit passes over a magnet, it will vibrate… Locating a magnet

4

It’s going to be hard keeping it the size of a quarter. But it is doable… With an Atiny85 some driving circuitry, it may be possible if you’re good with SMT components.

If you want, I could draw up a schematic fairly quickly. I may go ahead and do it so everyone else can use it…

5

Here ya go. This circuit is everything you need to run the motor and has the Sparkfun Reed Switch to Ground. You can program the '85 with a ICSP programmer or another Arduino if you have one. The only thing you need to add is the battery and motor (and the components of course). Note that this circuit has the '85 running at 8MHz so your code needs to reflect this due to timings. The code would be rather simple as well… Just make sure to burn a bootloader that will set the correct fuses and for the 8MHz internal oscillator.

Now you can see that the circuit will make it hard to be the size of a quarter but it is possible with SMT…

6

Don’t even need the micro. Replace the 2n2222 with the reed switch.

7

Sure, the reed switch could turn it on, but what would turn it off? I am assuming that he wants specific timings.

8

I second the reed switch + battery + motor suggestion.