Color display circuit

In the teaching of color TVs, in order to let students understand the color synthesis principle of color TVs. The use of this circuit can be beneficial to intuitive teaching,
reproduce color signals realistically, and receive good teaching effects. Thus breaking the synthetic abstraction of color.
    (1) The working principle circuit is as shown in the figure. It is based on the imaging remote circuit of color TV and uses light-emitting diodes to form a color synthesis
circuit.
    In the figure, VT1 is a red light-emitting diode drive circuit,
VD1~VD3 are ultra-high brightness red light-emitting tubes, and the operating current is designed
to be o~30mA (depending on the characteristics of the light-emitting diode), R. ,
RP1 is the base bias resistor of VT1. By adjusting RP1, the operating current flowing through the light-emitting diode can be changed , and the brightness of
the red light-emitting diode can be changed .
VT2 is a green light-emitting diode drive
circuit. VT3 is a blue light-emitting diode drive circuit, and VT4 is
a brightness adjustment circuit.
    R4 and RP4 are the base bias circuit of VT4. Adjusting RP4 (that is, adjusting the collector current of VT4) can change the current
flowing through the red,
green, and blue light-emitting tubes , thus changing the brightness of the three-color light-emitting tubes.