Infrared remote control dimming circuit

When the infrared receiving tube receives the remote control signal from the transmitter, the ⑦ pin outputs a low level after being processed by KA2184. This low level
is directly added to the base of VT to turn it on, and the current output by its collector forms a high level output at the upper end of R4. This high level
is added to the auxiliary input terminal (⑥ pin) of the dimming circuit LS7232 through RB as a dimming control signal.
    The receiving circuit is as shown in the figure. It is an infrared remote control dimming circuit . When its ⑥ pin inputs a trigger signal, its ⑧ pin will
continuously output control pulses that control the conduction angle of the bidirectional thyristor, causing the bidirectional thyristor to conduct. The angle varies between 410-1600. As
the conduction angle of the triac changes, the light changes from dark to bright or from bright to dark, thus achieving dimming control of the light.
    During the dimming process, when you need the light to change from dark to bright, you can press and hold the transmit button on the remote control to continuously send control signals. At this time, you can see that
the lamp is gradually getting brighter. When the required brightness is reached, immediately release the emission button, and the brightness of the lamp will stay at this position. If
you press it continuously, the light fork will gradually dim from bright to dark until it goes out.
    It should be noted that LS7232 is a PMOS type integrated circuit, so its power supply polarity is opposite to that of commonly used CMOS circuits, that is,
its VDD power supply terminal should be connected to the negative pole of the power supply, and the ‰ terminal should be connected to the positive pole of the power supply.
    The power supply of this circuit still uses AC power supply, capacitor C7 for step-down, and two-transistor VD1 for half-wave rectification. Different from other capacitor step-down power supply circuits
, the centimeter-drop capacitor C7 of this power supply is connected in parallel with a 2201uH inductor. Its function is to absorb the harmonics generated by the LS7232 and prevent
it from interfering with other electrical appliances through the power line. .