Section 1 Phase sequence detection of three-phase AC power supply and phase sequence locking circuit of three-phase load power supply

Double power supply circuit in the second quarter

Section 3 Control Circuits for Timing Power Supply and Intermittent Power Supply

Section 4 Automatic Power Limit Circuit

Section 5 Power Supply Overvoltage and Undervoltage Acousto-optic Alarm Circuit

Chapter II Electrical Measuring Circuit and Signal Circuit

Section 1 Current Measuring Circuit

Section 2 Voltage Measuring Circuit

Third power saving power measuring circuit

The fourth energy saving metering circuit

Section 5 Resistance Measuring Circuit

Section 6 Signal Circuit

Chapter III Motor Control Circuit

Section 1 Direct Starting Control Circuit of Three-phase Cage Induction Motor

Section II Control Circuit for Decompression Start of Three-phase Cage Induction Motor

Section 3 Braking and Protection Circuit of Three-phase Cage Induction Motor

Section 4 Control Circuit of Three-phase AC Wound Induction Motor

Chapter IV Electrical Control Circuits of Common Electromechanical Equipment

The first section C650 horizontal lathe electrical control circuit

Section 2 Electrical Control Circuit of M7 120 Surface Grinder

Section 3 Electrical Control Circuit of Z3040 Radial Drilling Machine

Section 4 Electrical Control Circuit of Water Supply and Drainage Pump

Section 5 Electrical Control Circuit of Fire Pump

Section 6 Electrical control circuit of equipment used in the construction site

Section 7 No-load self-stop control circuit of AC welding machine

Eighth power-saving heating control circuit

Chapter V Electronics and Circuits

Section 1 Resistance-Capacitance Time Relay Circuit

Section 2 Proximity Switch Circuit

Proximity switch, also called proximity switch, is also called contactless travel switch. It can not only complete stroke control and limit protection, but also be a non-contact detection device, which can be used to detect the size and speed of parts, as well as the automatic connection of frequency conversion counter, frequency conversion pulse generator, liquid level control and machining program. It is characterized by reliable work, long service life, low power consumption, high repositioning accuracy, high working frequency and adaptability to harsh working environment.

Among all kinds of switches, there is an element-displacement sensor, which has the ability to "sense" the approach of objects. Proximity switch uses the sensitive characteristics of displacement sensor to close the object to control the switch on and off.

When something moves towards the proximity switch and approaches a certain distance, the displacement sensor will "sense" it and the switch will act. This distance is usually called "detection distance". However, different proximity switches have different detection distances.

Sometimes the detected objects move to the proximity switch one by one and leave one by one at a certain time interval, and so on. Different proximity switches have different response abilities to detected objects. This response characteristic is called "response frequency".

Section 3 photoelectric switch circuit

The photoelectric switch is a member of the sensor family, which converts the light intensity change between the transmitter and the receiver into the current change to achieve the purpose of detection. Because the output circuit and input circuit of photoelectric switch are electrically isolated, it can be used in many occasions.

A new generation of photoelectric switch devices manufactured by integrated circuit technology and SMT surface mounting technology have intelligent functions such as delay, broadening, external synchronization, anti-interference, high reliability, stable working area and self-diagnosis. This new photoelectric switch is an active photoelectric detection system electronic switch with pulse modulation. It uses cold light sources, such as infrared light, red light, green light and blue light. , can control the state and action of solid, liquid, transparent body, blackbody, software, smoke and other substances quickly and lossless.

The contact travel switch has some shortcomings, such as slow response speed, poor accuracy, easy damage to the detected object and short service life, while the transistor proximity switch has a short working distance and cannot directly detect non-metallic materials. The new photoelectric switch overcomes these shortcomings, and has the advantages of small size, multi-function, long life, high precision, fast response, long detection distance, strong anti-optical, electrical and magnetic interference.

This new photoelectric switch has been used in many fields, such as crop liquid level detection, liquid level control, product counting, width discrimination, speed detection, fixed-length shearing, hole identification, signal delay, automatic door induction, color code detection, punching machine and shearing machine, safety protection and so on. In addition, it can also be used as an anti-theft alarm in banks, warehouses, shops, offices and other necessary occasions by taking advantage of the concealment of infrared rays.

The fourth quarter thyristor switch circuit

Section 5 Solid State Relay Circuit

Section 6 Leakage and electric shock protection circuit

Section 7 Motor Protection Circuit

Chapter VI Lighting and Lighting Control Circuits

The first section lighting circuit

Section 2 Electronic Ballast Circuit

Section 3 Control Circuit of Sound, Light and Touch Lights

The fourth quarter decorative lamp control circuit

Section 5 Circuit of Optically Controlled Street Lights and Road Warning Lights

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