Small wireless sound reinforcement system 02

The device actually consists of two parts: transmitting and receiving amplification. The circuit principle of the transmitting part is shown in Figure 6.28. It is actually a
high-fidelity, high-sensitivity FM wireless microphone. We have seen many articles about the production of FM wireless
microphones before, and the selection of microphones all used small condenser microphones. However, this kind of microphone has a narrow frequency band and is prone to feedback and howling. Since the output impedance of a dynamic
microphone is lower than that of a condenser microphone, a transistor preamp plus an IC amplifier
circuit , as shown in Figure 6-28. Microphone The signal picked up by the MIC is coupled to VT1 through Cl for preamplification and Icl power amplification, and then used as
the signal source of the oscillation tube VT2. The early VT is vertically connected to a common IJC. Oscillation circuit, its stable operating point is obtained by R6. The modulated
signal is sent to VT3 by clo for buffer amplification -. ． ． to, the influence of multiple human bodies on oscillation stability and the work of increasing the device