Using timer to judge the quality performance circuit diagram of optocoupler

Photocoupler

Using timer to judge the quality performance of optocoupler
The circuit used is shown in Figure 1. The function of VD1 and VD2 is to separate the charge and discharge circuits of capacitor C1 (with a capacitance of 10uF) so that the timer outputs a pulse waveform with adjustable duty cycle; C2 is Filter capacitor, the capacitance value is 0.01uF, its role is to form the timing component; R1, R2 resistance is 10kΩ and 51kΩ; Rp resistance is 0-10kΩ; R3, R4 resistance can be taken as 2kΩ and 1kΩ , their role is to limit the flow;
Vcc can use dry battery or DC regulated power supply.
The detection steps are as follows:
After power-on (Vcc=5V or 6V), if the LED of the LED flashes at a frequency of about 2Hz, the quality of the tube under test is good. The reason is:
After power-on, the timer will output the pulse voltage from the 3-pin (this voltage is related to the value of Vcc. This pulse voltage is applied to the photocoupler LED through resistor R3. The oscillation frequency is f=2Hz. The above phenomenon occurs. This circuit can adjust the illumination time interval of the LED.
note:
1. This circuit can remove VD1, VD2 and sliding rheostat Rp, so that the 5 timer will output the pulse waveform with the same duty cycle;
2, the output pulse frequency of the timer can not be too high, otherwise it will be found that the state of the LED is always on, thus affecting the viewing effect.