jbelectric777
- Nov 29, 2012
- 32
- Joined
- Nov 29, 2012
- Messages
- 32
I wanted to know if a 555 will provide enough oscillation to send through an inductor and antenna and reach a receiver 15 feet away to turn on an LED.
You are quite correct. Here is a nice article by Texas Instruments describing what is allowed in the US for unlicensed purposeful operation at low power levels. It explicitly forbids any purposeful radiation from 399.9 to 410 MHz, and 433 MHz is quite close to that band of frequencies. However, I believe that equipment meeting certain FCC Part 15 requirements could operate legally at 433 MHz in the US. Still, 1.2 GHz modules are also common. See this Google results page.Regarding 433MHz modules. If he lives in the US these are not legal. Okay in Europe.
1.2GHz modules are okay in the US.
Bob
Simple is always better. I forgot that AM/FM "pocket radios" are dirt cheap now. Easy to build a little broadcast band one-transistor transmitter and modulate it with the 555 pulses. The circuits were all over the "hobby magazines" in the 1970s, and earlier than that if you built your own two-transistor transmitter. IIRC both AM and FM were popular.The output of the 555 drives a transistor that is configured as an oscillator and it gets a pulsed signal. The output of the transistor can be detected up to 200 metres.
The output of the receiver will be a tone and this is picked-off the speaker to illuminate a LED.