I want to start building a distance sensor project. Basically, the sensor has two parts. Whenever the two parts are separated by a certain distance, then one of the parts will light up.

The first part will need to emit certain signal all the time. While the second part will need to receive the signal and light up when there is no signal. I hope that the first part will not use too much energy and preferably can operate with solar energy.

Any idea how should I start this project?

 

Hello,

You could use a permanent magnet for the first part.(uses no energy at all).
You could use a hall sensor on the second part.
When the field is getting to low you could trigger a circuit to light the light.

Here is a page on hall sensors from the EDUCYPEDIA.
http://www.educypedia.be/electronics/sensorshall.htm

Greetings,
Bertus

 

A good start would be letting us know the max. seperation desired, and what type of playing field, any obstructions? Hall effect is reliable in the 1/4 in. range, then IR, sonic, & RF. Might consider a rotating "beacon" to conserve power, with max. output; receiver would use a missing pulse detector.

 

Hello,

The sensitivity of a hall sensor can be very good.
I have used the kmz10 several times.
The kmz10 is a bridge that can be made very sensitive.
I used it to sense the 5 gauss line at an nmr magnet.
( the safe aera is outside the 5 gauss line).

Greetings,
Bertus

 

Thank you for all the advice.

I am actually thinking to make it into a product which can be attached to any object you want and the separation distance should be around 3-5m. It is kind of an anti-theft and a anti-forget product.

 

Hello,

At that distance my hall sensor will not work.
Perhaps use a very small transmitter.
The power of the transmitter determines the distance to the reciever where it stil can be "heard".
If the signal strenght is becoming to weak you could trigger your "alarm".

Greetings,
Bertus