Assembly line outage monitoring circuit

Some automatic production lines need to monitor the situation of conveying materials. In some production processes, material interruption is considered an accident, and in some cases, material blockage is also considered an accident. Simple material monitoring problems can be solved by using "dark
control circuit " or "light control circuit
". However, the transmission of materials in some production processes is intermittent . This cannot be monitored with simple "dark on" and "light on" circuits. A delay circuit must be used to identify whether the material is really broken or falsely broken, and
alarm and control are carried out when the material is really broken.
    (1) Material outage monitoring circuit Figure 7-14 is a material outage monitoring circuit diagram. The photoelectric conversion part is composed of VT2 and VT3. The material
passes between the light source HL1 and the photosensitive transistor, constantly blocking the light, so that the voltage of the capacitor G has no time to rise. VT4 is in a cut-off state, VT5 is also in
a cut-off state, and J2 cannot be closed.
    When the material is out of stock. Light shines on the phototransistor VT2 for a long time. The internal resistance of VT2 becomes smaller, providing sufficient base current to VT3.
VT2 is turned on, and the power supply charges G through RP. When the voltage on C rises to a certain value, VT4 and VT5 turn on. J2 suction table, the normally open
contact of J2 is closed to control the external circuit or alarm. G and RP form a delay circuit to identify the authenticity of the broken material. Because the operation of some physical debates is intermittent
. It is normal for a short period of time (such as 1~2s) to occur. The voltage on Ca does not rise much and cannot reach the level before VT4 is turned on.
When the material continues to run, it blocks the light and the voltage on G passes through the wall again. Let go and adjust RP to change the allowable time for normal material breakage.
    VT1 forms the light source switching and alarm circuit . When HL1 is working normally, the voltage across it is about 6V, and the breakdown voltage of VD is about 8V.
7. So VT1 cannot conduct. And when HL1 is damaged, r filament is broken). The 12V voltage passes through Shuhehu to cause VD to break down and conduct electricity; VT1 is turned
on and the backup light HL2 is lit, achieving the purpose of automatic switching. At the same time, J1 is closed, and the normally open contact of Jl is closed and the bell alarm is controlled, prompting the operator
to change the light bulb.