One hertz is one cycle per second, meaning repeating cycle as an event. For example, hertz is applied physics measuring the number of times for a second wave (either acoustic or electromagnetic) is repeated or can be applied, among other uses, to ocean waves that reach the Beach vibrations per second or a solid. The quantity that measures the frequency hertz is called,in this regard, the inverse of the period. One hertz is an oscillation frequency of suffering a particle over a period of one second.

The lux (symbol lx) is the derivative unit of the International System of Units for the illuminance or lighting level. Equal to one lumen/m². It is used in photometry as a measure of luminance, taking into account the different wavelengths by the luminosity function, a standard model of the light sensitivity of the human eye.

IP65 Although it seems very complicated nomenclature IP standards is only one division in two digits, where each digit indicates that it is being served to meet these regulations. For the first digit would be: 0 No protection 1 element to be used for testing (sphere 50 mm in diameter) should not get to go completely. 2 element to be used for the test (area of ??12.5 mm diameter) should not get to go completely. 3 element to be used for testing (sphere 2.5 mm in diameter) must not come at all. 4 element to be used for the test (sphere of 1 mm in diameter) must not come at all. 5 ingress of dust can not be avoided, but it must not enter an amount that interferes with the proper functioning of equipment. 6 polvo should not come under any circumstances in the case of the second digit: Level Protection Against Expected Results Test Method 0 The water enters the equipment quickly. 1 The equipment is placed in their usual work. Should not enter the water when it is dropped from 200 mm height from the team for 10 minutes (at a rate of 3-5 mm³ per minute) 2, the equipment is put into lugar normal work. You should not enter the water when the leaves fall, for 10 minutes (at a rate of 3-5 mm³ per minute). This test should be performed four times at a rate of one for every 15 ° rotation both vertically and horizontally, starting each time the normal position. 3 The equipment is placed in their usual work. You should not enter the water spray at an angle up to 60 ° right and leftvertically to an average of 10 liters per minute and a pressure of 80-100kN/m for a time not less than 5 minutes. 4 The equipment is placed in their usual work. You should not enter the water thrown from any angle to an average of 10 liters per minute and a pressure of 80-100kN/m for a time not less than 5 minutes. 5 The equipment is placed in their usual work. Should not enter waterthrown jet (from any angle) by means of a nozzle 6.3 mm in diameter, at an average of 12.5 liters per minute and a pressure of 30 kN/m for a time not less than 3 minutes and a no closer than 3 meters. 6 The equipment is placed in their usual work. You should not enter water squirted (from any angle) through a nozzle diameter of 12.5 mm, an average of 100 liters per minute and a pressure of 100 kN/m² for at least three minutes at a distance of not less than 3 meters. 7 The object must endure without any filtration complete immersion in 1 meter for 30 minutes. 8 electrical/electronic equipment must withstand (without filtration) complete and continuous immersion depth and during the time specified by the manufacturer of the product with the agreement ofclient, but provided they are more severe than those specified for the value 7. For IP65 should meet the following standard conditions. Would hold cirscuntancias be dusty and prevent to enter under any cirscuntacia, and bear no powerful jets of water.

hen we talk about IP code (International Protection) we talk about an international standard (IEC 60529) which classifies the protection against external factors, solid or liquid, that has a component or electronic device; LED strips, controllers, meters, security cameras, etc.

This alpha-numerically standard has been designed to sort different levels of protection. Nomenclature starts with IP followed by two numeric values.

- Example IP68:

The first value ranges from 0 to 6 and indicates the protection against solid agents. In this case, strong protection against dust.

The second value is between 0 and 8 and indicates the protection against liquid agents. In this case the complete and prolonged immersion during the time specified by the manufacturer.

We could say that the larger the number is greater IP protection has a device.

In below table, we can see different IP protections levels available.

IPXX	First digit (IPxx)	Second digit (IPxx)
0	Unprotected.	Unprotected.
1	Protection against objects of> 50 mm diameter.	Protection against vertically dripping water.
2	Protection against objects of> 12.5 mm diameter.	Protection against inclined drip water up to 15°.
3	Protection against objects of> 2 mm in diameter.	Protection against water projected from any direction, up to 60°.
4	Protection against objects of> 1 mm in diameter.	Protection against splashing water any direction.
5	Ingress of dust is not entirely revented, but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment .	Protection against water jets.
6	Dust tight.	Protection against strong jets of water.
7		Protection against complete immersion up to 1 meter for 30 minutes.
8		Protection against complete and prolonged immersion.

VAC would be the abbreviation of Volt Altern Current which would be translated Volts of alternating current. The difference between VDC is that its sinusoidal oscillation achieving a more efficient energy transmission.

The alternating current is the energy that we receive in our homes, it is generated in the power plants by means of alternators.

The intensity of this type of current varies with time, and changes direction 50 times throughsecond (50hz). The generated voltage changes in the form of sine wave so it is not constant.

In the image:

1. Current by pulsations.
2. Direct current (DC).
3. Alternating current (AC).
4. Variable current.

Within the detection systems we can find different types according to their operation, among them the most common:

1. Infrared sensors
2. Vibration sensors.
3. Photoelectric sensors.
4. Ultrasound sensors.
5. Acoustic sensors

Each type of sensor uses different detection methods and each one is recommended according to the situation.

1. Sensors by infraRrojos, are one of the most used types, thanks to its reliable operation and installation, since we can find this type of wired and wireless sensors.
   The infrared sensor has a phototransistor capable of detecting the infrared electromagnetic radiation emitted by a body, this type of radiation is not visible by the human eye. A change of radiation in its perimeter will activate the relay and proceed to send ato alarm signal.
   Within these, there are two models, passive infrared sensor, which only has a phototransistor and assets, which have an emitter and a receiver.
2. Vibration sensors are used mostly in security systems, such as window sensors. car alarms etc.
   Its operation is based on an accelerometer, through a piezoelectric sensor. This type of sensorDue to its construction material it allows to detect changes and pressure when emitting an electric charge.
3. Photoelectric sensors, these are the sensors that use photoelectric rays, normally a transmitter and a receiver are used, they are commonly used in automatic door systems, elevator doors, production chains, etc.
4. The ultrasonic sensors are those that emit an acoustic signalabout 30 kHz, a signal that is not appreciated by humans. This signal or wave propagates through space, walls, objects, doors, etc. once the signal has spread the sensor is activated and any change will trigger the sensor.
   These types of sensors are also used in devices that require measuring distances and detecting objects.
5. Acoustic sensors, are those that can detect the signal emitted by anyobject and are able to detect the pressures that the acoustic waves emit, such as the noise of the crystals when breaking a window.