What are the application ranges of RF Divide couplers

　　1. Composition of switch circuit

　　When the input signal ui is at a low level, transistor V1 is in an off state, and the current of the light-emitting diode in optocoupler B1 is approximately zero. The resistance between output terminals Q11 and Q12 is very high, which is equivalent to the switch being "disconnected"; When UI is at high level, v1 conducts and the light-emitting diode in B1 emits light. The resistance between Q11 and Q12 decreases, which is equivalent to the switch being "turned on". This circuit is in a high-level conducting state because Ui is at low level and the switch is not connected. Similarly, when there is no signal (Ui is at low level), the switch conducts, so it is in a low-level conducting state

　　2. Composition of Logic Circuits

　　The circuit is an AND gate logic circuit. The logical expression is P=A.B. In the figure, two phototransistors are connected in series. Only when the input logic levels A=1 and B=1, the output P=1. Similarly, logic circuits such as "OR gate", "NAND gate", and "OR NOT gate" can also be formed

　　3. Form an isolated coupling circuit

　　A typical AC coupled amplifier circuit. By selecting the appropriate current limiting resistor Rl for the light-emitting circuit, the current transfer ratio of B4 can be kept constant to ensure the linear amplification effect of the circuit.

　　4. Form a high-voltage voltage regulator circuit

　　The driving transistor needs to use a transistor with high voltage resistance (the driving transistor in the figure is 3DG27). When the output voltage increases, the bias voltage of V55 increases, and the forward current of the light-emitting diode in B5 increases, causing the inter electrode voltage of the photosensitive tube to decrease. The bias voltage of the junction of the tube is adjusted to decrease while the internal resistance increases, resulting in a decrease in the output voltage while maintaining its stability

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