VDC would be the abbreviation for Volt Direct Current which translated would volts direct current. The idea of ??this type is unidirectional current to the load. Direct current is normally produced by batteries, thermocouples, solar cells and a dynamo electric machine type. The direct current can flow in conductors such as wires, but may also flow through semiconductors, insulators ... In the image: 1 - current per pulse 2 - Direct Current (DC) 3 - Alternating Current (AC) 4 - Variable Current

If we talk about industrial automation we will find different terms related to the design of the internal circuit and the type of transmitter. PNP and NPN are two so-called bipolar or called (BJTs) transistors. These transistors that are controlled by current allow basically the amplification of the same through the circuit. Both PNP and NPN have the same function, provide amplification of the currentAnd/or switching. The only difference between them is the way in which the current or energy is assigned to each of its connectors.

• PNP (sinking or Pointing iN Proudly) is one of the types of transistors most used in electrical circuits, this type of transistor differs in that it receives positive voltage at its emitter terminal and negative voltage at its base terminal. Positive voltage to the transmitter allowsThe current flows from the emitter to the collector, since there is negative current to the base. As the voltage goes down from the base the transistor is on and conducts through the power at the output load.
• NPN (Sourcing or Not Pointing iN) is another transistor, unlike the PNP it is faster in its switching, since it works with reference 0V, it has less immunity to the noise and a smaller fall of tenZion. This type of transistor works in a completely opposite way to PNP. The NPN transistor receives positive voltage at the collector terminal. This positive voltage allows current to flow through the collector to the emitter, as there is enough base voltage to power the transistor. As the current increases at the base, the transistor is activated more and more until it is completely driven from the collector to the emitter and encoderGo the circuit. The opposite happens when the voltage decreases from the base, until the current is so low that the transistor no longer leads through the collector to the emitter and shuts off.

These are two types of contacts widely used in electrical installations and circuits. Distinguishing the difference of these two types is very simple.

• A NO (normally open) type contact is one that does not let the current flow while the same or the device is in standby or standby mode. The most common type NO contact is eg house switches, which remain open (not closedCircuit) until the switch is pressed.
• The NC contacts (normally closed) are the opposite of the NO contact, they let the current pass while they are in standby or at rest to be actuated. An example would be a thermal protection relay of a motor, which remains closed while there is voltage.

Proximity or range sensors are used in many installations requiring an action according to the distance (D) of an object.
They are also used in robotics to control the movement according to the environment, in motorized or domotic installations, the applications can be many and very different.
There are a variety of proximity sensors, including the most common are position switches, Capacitive sensors, inductive sensors, photoelectric sensors where an emitter (E) and a receiver (R), ultrasonic sensors and magnetic sensors are required.
Each of these sensors have the same function, but each of them uses different systems for the detection, either by contact, sound, etc.
Its detection capacity varies according to the type of sensor, and can vary from millimeters to meters. We can vEr these sensors in automatic floor cleaning systems, safety barriers, rear parking sensors for cars, mobile phones, etc.

Inductive proximity sensors are used for detection of ferrous materials, are used to a large extent in companies that need control of presence or absence of ferrous materials in an object, counting or positioning.
This type of proximity sensors emit a magnetic signal to the ferric object, calculate the distance by detecting the loss of magnetic current that is absorbed by the object.
TheSensor consists of a coil inside its ferrite, a level sensor, an oscillator and the action circuit, its function is simple and similar to the capacitive sensor, the magnetic proximity sensor uses a coil to emit an electromagnetic signal to the object Metal, the oscillator is responsible for calculating the capacity to preserve its magnetic properties, by calculating energy loss andThe oscillation amplitude will calculate the distance and the trigger will generate the signal that changes to the status sensor to ON and OFF.
A: Coil
B: Active surface
C: Magnetic field
D: Indicator Led