Pneumatic proximity sensors actuated by a magnetic field; they have been designed typically for use in detecting pneumatic cylinder intermediate or end stroke positions; additionally, pneumatic proximity sensors are used for the contactless sensing of iron (Fe) parts within similar applications.
Pneumatic systems are like hydraulic systems, but they use compressed air instead of a fluid to transmit power. They rely on a constant source of compressed air to control energy and actuate motion devices.
Inductive Proximity Sensors are roughly classified into the following three types according to the operating principle:
Principles of operation
A proximity sensor detects the approach of an object without making a contact.
There are three types of proximity sensors :
1) High-frequency oscillation type using electromagnetic induction.
2) Magnetic type using magnetism.
3) Electrostatic capacity type which senses the changes in the electrostatic capacity between the sensing object and the sensor.
1. The high-frequency oscillation type using electromagnetic induction:
Principle of high-frequency oscillation type inductive proximity sensor
The detection coil located at the front end of the sensor produces a high-frequency magnetic field as shown in the figure below. When an object (metallic) approaches this magnetic field, induced currents flow in the metal, causing thermal loss and resulting in the reduction or stopping of oscillations.
This change in state is detected by an oscillation state sensing circuit which then operates the output circuit.
2. The magnetic type using a magnet:
The most common type of sensor used for pneumatic cylinders are magnetic proximity sensors, which detect the magnetic field of a magnet integrated in the cylinder piston. The sensor is mounted onto the pneumatic cylinder's body and will indicate “ON” or “OFF” based on proximity to the magnet.
If you use more than one sensor, you can loop each other.
SMPS stands for Switched-Mode Power Supply. It is an electronic power supply that uses a switching regulator to convert electrical power efficiently. It is also known as Switching Mode Power Supply. It is power supply unit (PSU) generally used in computers to convert the voltage into the computer acceptable range.
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Short for Switched-Mode Power Supply, SMPS is a power supply that uses a switching regulator to control and stabilize the output voltage by switching the load current on and off. These power supplies offer a greater power conversion and reduce the overall power loss.
The SMPS or Switched Mode Power Supply electronic circuit converts power either with the use of switching devices that turn on/off at high-frequencies or with the help of inductors or capacitors to supply power when the switching device is in non- conduction state.
SMPS power supply is widely used in electronic equipment namely computers and several other devices which need efficient and stable power supply. Besides overall performance, SMPS have plenty of advantages which range from its size, cost, weight to efficiency.
Simply put, SMPS circuit converts and regulates energy with power semiconductors that are switched on/off with high-frequency. The different types of SMPS are:
1. DC-DC Converter
The power received from AC mains is rectified and filtered as a high-voltage DC. This high voltage DC voltage is then switched and fed to the step-down transformer at the primary side. At the secondary side of the step-down transformer the rectified and filtered output is collected which is ultimately sent as the output to power supply.
Irrespective of if the transistor is conducting or not the choke carries the current in forward converter. The diode inside the transistor carries the current during the OFF period to support the energy flow through the load. During the On period, the choke stores the energy and also passes a part of the energy to the output load.
The forward converter is a DC/DC converter that uses a transformer to increase or decrease the output voltage and provide galvanic isolation for the load. With multiple output windings, it is possible to provide both higher and lower voltage outputs simultaneously.
3. Flyback Converter
In a Flyback converter, during the On period of the switch magnetic field of the inductor stores energy. When the switch is in the open state the energy is emptied into the output voltage circuit. The Duty cycle in the Flyback converter is determined by the output voltage.
3. Flyback Converter
In a Flyback converter, during the On period of the switch magnetic field of the inductor stores energy. When the switch is in the open state the energy is emptied into the output voltage circuit. The Duty cycle in the Flyback converter is determined by the output voltage.
A flyback converter transforms a DC voltage at the input to a DC voltage at the output. The operating principle is similar to the buck-boost converter, but an additional transformer is.used to achieve galvanic isolation of the input and output.
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The flyback converter is used in both AC/DC and DC/DC conversion with galvanic isolation between the input and any outputs. The flyback converter is a buck-boost converter with the inductor split to form a transformer, so that the voltage ratios are multiplied with an additional advantage of isolation. When driving for example a plasma lamp or a voltage multiplier the rectifying diode of the boost converter is left out and the device is called a flyback transformer.
4. Self-Oscillating Flyback Converter
It is based on the Flyback principle. During conduction, a current through the transformer primary starts to ramp up linearly with the slope Vin/Lp. Due to the voltage induced in the feedback winding and the secondary winding the fast recovery rectifier start to operate in reverse biased and hold the conducting transistor ON.
The core begins to saturate once the current reaches its peak value. The result is a sharp rise in current is not supported by the fixed base drive supported by feedback windings. Hence, the switching begins to come out of saturation.
4. Self-Oscillating Flyback Converter
It is based on the Flyback principle. During conduction, a current through the transformer primary starts to ramp up linearly with the slope Vin/Lp. Due to the voltage induced in the feedback winding and the secondary winding the fast recovery rectifier start to operate in reverse biased and hold the conducting transistor ON.
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The self-oscillating flyback converter, often referred to as the ringing choke converter (RCC), is a robust, low- component-count circuit that has been widely used in low- power off-line applications. ... Therefore, the circuit operates with a variable switching frequency.
Advantages Of SMPS Circuit
1. Highly-efficient with lower levels of energy being dissipated as heat.
2. Useful in voltage step up and step down applications as they provide with high-efficiency voltage conversions.
1. Highly-efficient with lower levels of energy being dissipated as heat.
2. Useful in voltage step up and step down applications as they provide with high-efficiency voltage conversions.
3. The capacitance type using the change in capacitance :
1. Material density: Most of plastic material is not detectable by a capacitive proximity sensor at a proper distance, sometimes becasue the density is low , sometimes because the plastic is too thin, for example, if you detect an empty 1mm thick plastic bottle, the detecting distance may be less than 2mm , if you fill the bottle with water ,then the detection distance could be longer than 5mm.
2. The Sensitivity: when the sensor cannot work, there is a sensitivity-adjustment screw on the back of the sensor, you can turn it clockwise with a flat head screwdriver to increase the sensitivity of the sensor
3. Load Current: High output current can result in prodct failue, Inductive load (for instance, motors which draw high current when started) is not allowed to be directly connected with this sensor, because this sensor can only provide 400mA current for the load , you can use this sensor to provide a low level signal for a PLC which requires very little current ,or you can control a small relay that requires a coil current less than 400mA.
2. The Sensitivity: when the sensor cannot work, there is a sensitivity-adjustment screw on the back of the sensor, you can turn it clockwise with a flat head screwdriver to increase the sensitivity of the sensor
3. Load Current: High output current can result in prodct failue, Inductive load (for instance, motors which draw high current when started) is not allowed to be directly connected with this sensor, because this sensor can only provide 400mA current for the load , you can use this sensor to provide a low level signal for a PLC which requires very little current ,or you can control a small relay that requires a coil current less than 400mA.
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