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The Function Of Coupler
Sep 06, 2018

1.Switch circuit

When the input signal UI is low level, the transistor V1 is in the cut-off state, the current of the light-emitting diode in the photocoupler B1 is approximately zero, and the resistance between the output Q11 and Q12 is very large, which is equivalent to the switch "off"; when the UI is high level, V1 is turned on, the resistance between the light-emitting diode in B1, Q11 and Q12 is reduced, which is equivalent to the switch "off". The switch is on because the Ui is low level and the switch is not on, so the circuit is in a high level conduction state. Similarly, when there is no signal (Ui is low level), the switch is on, so it is in a low level conduction state.

2. composing logic circuit

The circuit is "and gate" logic circuit. The logical expression is P=A.B. In the diagram, two phototransistors are connected in series, and the output P=1 is obtained only when the input logic level A=1 and B=1. Similarly, the logic circuits such as OR gate, NON gate, OR NON gate can be formed.

3. isolation coupling circuit.

The circuit is shown in Fig. 4. This is a typical AC coupled amplifier circuit. The linear amplification of the circuit can be guaranteed by properly selecting the current limiting resistance Rl of the luminous circuit and making the current transfer ratio of B 4 constant.

4. constitute high voltage regulator circuit

A high voltage withstand transistor is required for the driving tube (the driving tube is 3DG27). When the output voltage increases, the bias voltage of V55 increases, the forward current of the diode in B5 increases, the voltage between the photodiode decreases, the bias voltage of the adjusting tube be junction decreases and the internal resistance increases, so that the output voltage decreases and the output voltage remains stable.

5.Automatic control circuit for lighting of hall

A is a set of four analog electronic switches (S1 ~ S4): S1, S2, S3 in parallel (can increase driving power and anti-jamming ability) for the delay circuit, when it is connected to the power supply, R4, B6 drive bidirectional thyristor VT, VT directly control hall lighting H; S4 and external photosensitive resistance Rl constitute the environment light detection circuit. When the door closes, the normally closed dry reed KD mounted on the door frame is acted on by the door magnet, and its contacts are disconnected. S1, S2, S3 are in the open state of data. In the evening, the owner comes home and opens the door. The magnet is away from KD and the KD contacts are closed. At this point, the 9V power supply is charged to C1 via R1, and the voltage at both ends of C1 rises rapidly to 9V. The rectifier voltage, through S1, S2, S3 and R4, makes the luminescent tube in B6 emit light and triggers the bidirectional thyristor to turn on, the VT to turn on, and the H to light up, thus realizing the automatic lighting control. When the door closes, the magnet controls the KD, the contacts are disconnected, the 9V power supply stops charging the C1, and the circuit enters a delayed state. C1 begins to discharge R3. After a period of delay, the voltage at both ends of C1 decreases gradually to below S1, S2 and S3 (1.5v), and S1, S2 and S3 return to the state of disconnection, resulting in B6 cut-off, VT cut-off, and H extinguishing to achieve the function of delayed shutdown.

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