I'm studying at a technical college in Denmark, and I'm doing an exam project involving emergency calls for elders. I'm currently trying to build a solution, but it involves a transmitter which can transmit at least 50 meters. Is there any way to do this? I'm not that experienced with electrical stuff, but know the basics. Any help is appreciated! :)
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2wireless or with wires? – Nils Pipenbrinck Apr 29 '15 at 08:15
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Wireless, would a bit bulky for the elders to run around with a wire ;) – Søren Eriksen Apr 29 '15 at 08:18
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Is this audio, or an invariable "I'm dying, help me!" signal? – Dzarda Apr 29 '15 at 08:34
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It's purpose is to call help. So no audio just indication – Søren Eriksen Apr 29 '15 at 08:35
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If it's just about indication of an emergency situation over a distance of 50m there is already a very simple solution available: portable air horn http://en.wikipedia.org/wiki/Air_horn – Curd Apr 29 '15 at 09:41
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Remember that efficient transmission depends upon the length of the aerial used and is related to wavelength (1/frequency) so choose a transmitter with a high frequency (say 800MHz +). – JIm Dearden Apr 29 '15 at 10:22
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I would recommend to use RF, since 50 meters are too much for simple infrared technology, and RF keeps being simple.
There are plenty example circuits to use by your own. Just search for RF Transmitter and Receiver.
http://pcbheaven.com/opendir/index.php?show=7471uk8807mj49773b5d
Guille
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Can you specify the parts? I need to order them, because I need to build it next week – Søren Eriksen Apr 29 '15 at 08:50
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To specify all the parts we would need to know more specifications about the project. How many people are intended to use this device? You would just use a LED for indication? Would you use batteries for the transmitter and a AC-DC converter for the receiver? – Guille Apr 29 '15 at 08:54
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One person is supposed to have a transmitter, which is wearable(as a bracelet or necklace), the transmitter will be using batteries. I will use a LED as proof of concept, and the receiver will be plugged in to the wall – Søren Eriksen Apr 29 '15 at 08:56
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