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Proximity alarm project

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New Member
Hey guys, new to this forum and would really appreciate your help :)

I am making an alarm which will trigger a buzzer from about 30ft away and a noise which will help you find the object that you had lost.

In perspective I am making a lost and found type of device. Whilst there are similar projects they are usually linked with mobile phones and defeats the objective of my brief.

Here's my example. I walk away from important object but I am carrying a buzzer as a object like a badge or necklace. The necklace or badge will buzz which tells me I am too far from the important object. The important object will have an alarming noise which will help me find the object again.

I don't really know where to start. Should I use Arduino?

Joe G

I seem to remember a similar design that used a short range rf circuit, when you lost the signal, it would turn on a buzzer.


Well-Known Member
Most Helpful Member
There is a product sold with a receiver that buzzes when your child with the transmitter wanders too far away. But the transmitter does not buzz to let you hear where it is.
Maybe let the receiver wander away and get lost then it buzzes to let you hear where it is.


Well-Known Member
Most Helpful Member

I think I found an existing idea however unsure how difficult it is to create this circuit yet. What do you guys think? It seems feasible.
Welcome to ETO, Neal9797!

Looks workable, to me. Maxim produces some outstanding products.

The difficulty will be in the construction of the circuit, i.e., (1) very small surface mount ICs (eg, 2.0 x 2.1mm size), and (2) difficult parts placement(s) due to the high frequency (915mHz) constraints.

Other than that, certainly seems to meet your design goal(s).


New Member
You can buy this on eBay for $10.00
Hi Colin,

Can you provide a link to it for me. Every single product I seem to view either has to link to a mobile phone or is basically detecting motion like an security alarm. I want the buzzer and noise input to be triggered when it has lost signal.

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