Switch noise cut off circuit

It is the switching impact noise cut-off circuit (the part inside the dotted box). The low-voltage AC on the secondary side of the power transformer is rectified and filtered by the diode and leads to pin 6 of the IC. According to the internal circuit structure of the STK4101II series IC in Figure 2-81 , pin 6 is the base of the squelch control tube. When a negative voltage is applied to pin 6, the squelch tube is turned on and the bias control tube is turned off. Force the front stage to stop working, thereby realizing the switch noise cut-off function.     The power supply of this machine does not need to be stabilized, but it is necessary to ensure that the power transformer has sufficient power, and the rectifier component must not be less than 3Ao