ElectoWorld

The 78XX voltage regulator The 78XX voltage regulator is one of the most common components on electronic boards. There are several models depending on the voltage or current you want at the output. This is called a linear regulator the last two digits give you the output voltage eg 7805 is a 5Vdc regulator, 7812 a 12Vdc regulator, their input voltage can go up to 35Vdc. A regulator is a 3-terminal component used to regulate voltage in an electrical circuit. Regulators are very useful in electrical circuits when you need a stable voltage. Indeed a regulator makes it possible to enter the output voltage very fixed, which is preferable for components such as microcontrollers. 7805 voltage regulator For example for a + 5V regulator, you will have a maximum drop to + 4.97V for high currents. Which is much more precise than batteries or a power adapter.     Above here is the usual circuit, the capacitors serving as an interference suppressor. The minimum input volt...

  The LM35 temperature sensor is an analog temperature sensor .This integrated circuit has 3 pins and generates an output voltage in linear relation with the temperature expressed in degrees Celsius The LM35 sensor is able to measure temperatures ranging from (-55 ° C to + 150 ° C) in its most precise version and with the right mounting, enough to measure any temperature. The analog output of the sensor is proportional to the temperature. It suffices to measure the voltage at the output of the sensor to deduce the temperature. Each degree Celsius corresponds to a voltage of + 10mV. The LM35 does not require any external calibration or size and maintains an accuracy of (+ / -0.4 ° C) at room temperature and (+ / - 0.8 ° C) over a range of 0-100° C. The temperature measured by the sensor is given by the relation: T = Vout / 10 with: T: Temperature [° C] Vout: Output voltage [mV]   DHT22 sensor The DHT22  temperature and humidity sensor communicates with ...

  A triac is made up of 2 thyristors placed head-to-tail in order to be bidirectional, usable in AC.It is also called solid state relay and it is the basis of dimmers. Is an active component increasingly used in today's assemblies. Its direct use on the sector makes it possible to switch large loads from much more modest circuits. Triac Symbol The three electrodes of the triac are called gate (control electrode), and MT1 and MT2 (for Anodes 1 and 2). These last two electrodes ensure the main conduction. Operation Once triggered by an impulse on the gate, the triac lets the current flow until this current falls below a critical threshold (holding current). Due to this structure, the triac is used to control the passage of the two halfwaves of an alternating current (while the thyristor only conducts during one halfwave). The circuit above is very simple trigger. The phase shifter network Rc charges the capacitor. when it reaches a voltage at the terminals, greater than the...

A variable resistor is a resistor whose value is variable.many factors can induce a variation of R according to its constitution. The most common are the following factors: Mechanical: Most often a variation in the length of the resistant body. These are strain gauges, Potentiometers or Rheostats. Thermal: The temperature to which the resistance is subjected (thermistor). We can find the Positive Temperature Coefficient resistance (the resistance increases when the Temperature increases) and the Negative Temperature Coefficient (the resistance decreases for an increase in T). Radiation: The radiation to which the resistance is subjected. (Many models exist, each one is sensitive to a specific radiation range). Chemical: A substance (gas, liquid, solid) brought into contact with the resistance. Electrical: the varistor is a resistor whose value drops from a threshold voltage. NTC Thermistors  Thermistors or resistors with negative temperature coefficient or N...

The thermistor is an element that detects temperature. It is made of a semiconductor material that captures all temperature changes. They have negative temperature coefficients. In this case, the resistance of the thermistor decreases when the temperature increases, this one is then also called NTC thermistor. When the Joule effect (heating due to the passage of current) is negligible, we can express a relation between the resistance of the NTC and its temperature by the following relation: The temperatures are  in degrees Kelvin, B and T0 are constants of the component.. NTCs are made from oxides of transition metals (manganese, cobalt, copper and nickel). These oxides are semiconductors. Characteristics: NTCs can be used in a wide temperature range, from -200 ° C to + 1000 ° C, and they are available in different versions: glass beads, discs, bars, pellets, washers, chips etc.  The nominal resistances range from a few ohms to a hundred kohms. The response time depends ...

a capacitor is a component made up of 2 parallel conductors, called plates separated over the entire extent of their surface by a thin insulator, expressed by its dielectric strength ε r (epsilon) or relative permittivity. The capacitor is an electronic component which has the particularity of being able to store energy when it is subjected to a voltage. This component is essential in the field of electricity, it is almost as common as resistance. Capacitor Symbol Charg e and energy stored in a capacitor The charge that can be stored in a capacitor of capacitance C in farad is given by the formula: Q =  C x  U The constants of this equation are : C: capacitor capacity in Farads (F) Q: capacitor charge in Coulombs (C) U: voltage across the capacitor in Volts (V) Definition of farad: capacitance of a capacitor containing 1 coulomb under 1 volt. The energy stored in joules can be calculated with:  Electrical model of real capacitors the manufacturing method and...

A photocoupler, or optocoupler is a device that allows two circuits to be connected and electrically isolated, we will have a control circuit with low currents which will drive a power circuit who will have current more important. how does an optocoupler work ? Provide galvanic isolation between two different circuits, while allowing the transmission of logical or analog information. The transfer of information between the two circuits takes place in a closed environment and is achieved by a luminous flux of wavelength l. The light is transmitted inside the case through a transparent plastic film. The LED lights up, the phototransistor receives light: the phototransistor is saturated  (switch closed). The phototransistor is not receiving light (the LED is off or an object interrupts the  light beam), the phototransistor is blocked (switch open) Why use an optocoupler? The role of an opto-coupler is either to provide galvanic isolation (no electrical connection) b...

Electromechanical relay An electromechanical relay is a switch controlled by an electromagnet. It is used to isolate the control circuit (which operates the electromagnet) and the power circuit (which is controlled by the switch) from each other. There is then no conductive connection which would allow the current flowing in the power circuit to damage the control circuit. R elay coil voltage For each relay, there is a coil voltage. It can be continuous (5V, 12V, etc.) or alternative (110V, 230V). This is the voltage that must be applied to the coil to switch the relay. The current consumed depends on the type of relay and is inversely proportional to the coil voltage. In a range of relays (5V, 12V, 24V, etc.), the power of the coil is constant For example: 12V 40mA, 24V 20mA, 48V 10mA, etc ... To determine the current consumed by the coil, simply measure the resistance with the ohmmeter and deduct the current. This is useful for dimensioning the power supply to the control (the ci...

The integrated circuit NE 555 enables the astable and monostable functions of long duration which allow the realization of time delays ranging from a few microseconds to a few hours.  Its performance and ease of use have opened up areas long reserved for electromechanics. The NE 555, which is in the form of an integrated circuit with 8 terminals, represents today one of the most used solutions for the generation of rectangular signals. ic 555 pin diagram As shown in the pinout in Fig1,  the 8 terminals of circuit NE 555 are: 1 ground (0 V supply) 2 trigger input 3 the main outlet 4 Reset input (Reset to Zero) 5 control output 6 threshold input 7 unloading exit 8 power supply (voltage VCC) the internal principle of 555: the Circuit NE 555 therefore has 3 inputs, 3  outputs, and 2 power supply terminals. We will call V2 the voltage present on terminal 2 (trigger), V6 the voltage on  terminal 6 (threshold), V5 the voltage on terminal 5 (control),...