Hi, can anyone help me with ideas on building devices that produce an audible signal when come close to each other, say 2 meters or less. Both devices continue signalling until they are two or more meters apart. Think about a microphone moved close to a speaker - you hear an unpleasant screeching sound until you move them apart.
Device requirements:
Portable: yes
Unit price: cheaper is better, max 5$ each.
Size: smaller is better, max cigarette-box-size.
Sensitivity: audible signal if distance between units is between 0 and around two meters. No signal if distance is more than that.
Power: battery operated
PS. I read some articles on the topic, including Bluetooth IPS - used in museums e.g. But that would probably cost $$$. For a non-tech like me, microphone-speaker setup seems appealing, but two-meter-range might be hard to achieve in a cheap and small device...
Any ideas?
Wertamaki
Device requirements:
Portable: yes
Unit price: cheaper is better, max 5$ each.
Size: smaller is better, max cigarette-box-size.
Sensitivity: audible signal if distance between units is between 0 and around two meters. No signal if distance is more than that.
Power: battery operated
PS. I read some articles on the topic, including Bluetooth IPS - used in museums e.g. But that would probably cost $$$. For a non-tech like me, microphone-speaker setup seems appealing, but two-meter-range might be hard to achieve in a cheap and small device...
Any ideas?
Wertamaki