I have finally started my journey of learning something new about our everyday radios and their functionality by making an AM radio transmitter using the 555 timer.
I am trying to understand how LC circuits work so I am currently not very expert in LC oscillator circuits, so I gave it a try with a 555 timer.
Here is the circuit:
- R1 = 680 ohm
- R2 = 470 ohm
- C1 = 1nf
The frequency of the circuit is somewhere between 850 and 1000 kHz.
I have tried this circuit with a 12 volt 7 ampere lead acid battery which yielded nice results.
The problem is, the transmitted audio can only be heard within 100cm or almost 1 meter radius from the transmitter. The audio quality is crystal clear if it is kept within 60cm. If I exceed this radius, the audio signal gets noisy and weaker. After the absolute 100 cm or 1 meter, the transmitter signal gets out of range.
If we puta thick obstacle between the transmitter and the radio, 60cm crystal clear radius reduces to almost half, 30 cm.
I tried to boost the signal like this:
This solution did not seem to work.
I need the range of this transmitter to be at least 5 - 10 meters. (range of 10-20 meters would be the best.) Currently it is working fine within 1 meter of radius without any obstacle.
How can I achieve the desired range with a good strength and what should the booster circuit look like?