800 m transmit circuit using a sound resonator ----- 800M FM Transmitter

Keywords: Sound resonator transmit circuit, digital transmit circuit 800m transmit circuitry using a sound resonator  Use a lot of wireless transmit circuits using a sound resonator, here is launched, this circuit is the season of the module introduced by this article 3 years ago, I combined with the article introduced by the article. After a mass production, some parameters have been improved, and now this product is really good. But now this Dongdong's imitation product is too much, the quality is also very big, but because it is relatively simple, I think it is still necessary to make it out to everyone, I also found a lot of similar circuit maps online, but Some of them have traps, I hope everyone should pay attention to learn to distinguish some bugs. For this module, I didn't test its absolute power of wireless transmission, but we took the car to pull out the road on the road. It coordinated with ordinary 315M ultra-regeneration reception modules, which can reach 800 meters from the distance, although my circuit As long as the value of the 8050 base resistance is reduced, the communication distance will increase to 1200 meters or even farther, but after a lot of experiment prove, it is not very reliable. I am not very clear, there may be 2 reasons, one It is 8050 when R2 is small, there is a slight conduction, causing the launch to be fast. Another one is that the R2 is small, and the 8050 open current is relatively large, and the power supply may be a disturbance, but does not reach the gas purity requirements. I have doubted that my circuit is very matched, so I bought a lot of similar modules called 1500 meters, I found that they also have the same unreliability, generally expressing occasionally can't start the same or the baud rate is less than 2K. Later, I added R2 resistance. When it was more than 15K, the launch has always been normal, the distance and 27k are almost, so now use this resistance, here L1L2, I am using 0.8mm free lacquered line in 3 mm drill bit The upper wrap is half a half.

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