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A long-range FM transmitter circuit (500M)

2016-04-11 05:52  
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A long-range FM transmitter circuit (500M)
In the circuit shown as Figure 1, the dedicated launch tube T2 and its peripheral components form a high-frequency oscillator with frequency range in 88 ~ 108MHz. The audio signal is picked up by electret microphone and amplified firstly by T1, then the amplified low-frequency signal modulates the high frequency carrier. If the electret microphone M disconnects, the output end connects player to send the music signal. Dedicated tube T2 for RF Transmitter selects FF501 which uses standard T0-92 package ( like the 9000 series of transistors ), and the shape and pin arrangement are shown in Figure 2, and ICM is 45mA, fT is greater than 1.3GHz, VCEO is 13V. The advantages of a dedicated tube include good consistency, greater RF output power, adjustment of circuit, FF501 can fully work in the higher frequency band.