Radio components - symbols on the diagram. How to read the designations of radio components on the diagram? We control stepper motors and DC motors, L298 and Raspberry Pi Examples for Arduino

Content:

Beginning radio amateurs are often faced with the problem of identifying radio components on diagrams and correctly reading their markings. The main difficulty lies in the large number of names of elements, which are represented by transistors, resistors, capacitors, diodes and other parts. Its practical implementation and normal operation of the finished product largely depend on how correctly the diagram is read.

Resistors

Resistors include radio components that have a strictly defined resistance to the electric current flowing through them. This function is designed to reduce the current in the circuit. For example, to make a lamp shine less brightly, power is supplied to it through a resistor. The higher the resistance of the resistor, the less the lamp will glow. For fixed resistors, the resistance remains unchanged, while variable resistors can change their resistance from zero to the maximum possible value.

Each constant resistor has two main parameters - power and resistance. The power value is indicated on the diagram not with alphabetic or numerical symbols, but with the help of special lines. The power itself is determined by the formula: P = U x I, that is, equal to the product of voltage and current. This parameter is important because a particular resistor can only withstand a certain amount of power. If this value is exceeded, the element will simply burn out, since heat is released during the passage of current through the resistance. Therefore, in the figure, each line marked on the resistor corresponds to a certain power.

There are other ways to designate resistors in diagrams:

1. On the circuit diagrams, the serial number is indicated in accordance with the location (R1) and the resistance value is equal to 12K. The letter “K” is a multiple prefix and means 1000. That is, 12K corresponds to 12,000 ohms or 12 kilo-ohms. If the letter “M” is present in the marking, this indicates 12,000,000 ohms or 12 megaohms.
2. In marking with letters and numbers, the letter symbols E, K and M correspond to certain multiple prefixes. So the letter E = 1, K = 1000, M = 1000000. The decoding of the symbols will look like this: 15E - 15 Ohm; K15 - 0.15 Ohm - 150 Ohm; 1K5 - 1.5 kOhm; 15K - 15 kOhm; M15 - 0.15M - 150 kOhm; 1M2 - 1.5 mOhm; 15M - 15mOhm.
3. In this case, only digital designations are used. Each includes three digits. The first two of them correspond to the value, and the third - to the multiplier. Thus, the factors are: 0, 1, 2, 3 and 4. They indicate the number of zeros added to the base value. For example, 150 - 15 Ohm; 151 - 150 Ohm; 152 - 1500 Ohm; 153 - 15000 Ohm; 154 - 120000 Ohm.

Fixed resistors

The name of constant resistors is associated with their nominal resistance, which remains unchanged throughout the entire period of operation. They differ depending on the design and materials.

Wire elements consist of metal wires. In some cases, high resistivity alloys may be used. The basis for winding the wire is a ceramic frame. These resistors have high nominal accuracy, but a serious drawback is the presence of a large self-inductance. In the manufacture of film metal resistors, a metal with high resistivity is sprayed onto a ceramic base. Due to their qualities, such elements are most widely used.

The design of carbon fixed resistors can be film or volumetric. In this case, the qualities of graphite as a material with high resistivity are used. There are other resistors, for example, integral ones. They are used in specific integrated circuits where the use of other elements is not possible.

Variable resistors

Beginning radio amateurs often confuse a variable resistor with a variable capacitor, since in appearance they are very similar to each other. However, they have completely different functions, and there are also significant differences in how they are represented on the circuit diagrams.

The design of a variable resistor includes a slider that rotates along the resistive surface. Its main function is to adjust the parameters, which consists in changing the internal resistance to the desired value. The operation of the volume control in audio equipment and other similar devices is based on this principle. All adjustments are made by smoothly changing voltage and current in electronic devices.

The main parameter of a variable resistor is its resistance, which can vary within certain limits. In addition, it has an installed power that it must withstand. All types of resistors have these qualities.

On domestic circuit diagrams, elements of variable type are indicated in the form of a rectangle, on which two main and one additional terminal are marked, located vertically or passing through the icon diagonally.

In foreign diagrams, the rectangle is replaced by a curved line indicating an additional output. Next to the designation is the English letter R with the serial number of a particular element. The value of the nominal resistance is indicated next to it.

Connection of resistors

In electronics and electrical engineering, resistor connections are often used in various combinations and configurations. For greater clarity, you should consider a separate section of the circuit with serial, parallel and.

In a series connection, the end of one resistor is connected to the beginning of the next element. Thus, all resistors are connected one after another, and a total current of the same value flows through them. Between the start and end points there is only one path for current to flow. As the number of resistors connected into a common circuit increases, there is a corresponding increase in the total resistance.

A connection is considered parallel when the starting ends of all resistors are combined at one point, and the final outputs at another point. Current flow occurs through each individual resistor. As a result of parallel connection, as the number of connected resistors increases, the number of paths for current flow also increases. The total resistance in such a section decreases in proportion to the number of connected resistors. It will always be less than the resistance of any resistor connected in parallel.

Most often in radio electronics, a mixed connection is used, which is a combination of parallel and serial options.

In the diagram shown, resistors R2 and R3 are connected in parallel. The series connection includes resistor R1, a combination of R2 and R3, and resistor R4. In order to calculate the resistance of such a connection, the entire circuit is divided into several simple sections. After this, the resistance values ​​are summed up and the overall result is obtained.

Semiconductors

A standard semiconductor diode consists of two terminals and one rectifying electrical junction. All elements of the system are combined in a common housing made of ceramic, glass, metal or plastic. One part of the crystal is called the emitter, due to the high concentration of impurities, and the other part, with a low concentration, is called the base. The marking of semiconductors on the diagrams reflects their design features and technical characteristics.

Germanium or silicon is used to make semiconductors. In the first case, it is possible to achieve a higher transmission coefficient. Elements made of germanium are characterized by increased conductivity, for which even a low voltage is sufficient.

Depending on the design, semiconductors can be point or planar, and according to technological characteristics they can be rectifier, pulse or universal.

Capacitors

A capacitor is a system that includes two or more electrodes made in the form of plates - plates. They are separated by a dielectric, which is much thinner than the capacitor plates. The entire device has mutual capacitance and has the ability to store electrical charge. In the simplest diagram, the capacitor is presented in the form of two parallel metal plates separated by some kind of dielectric material.

On the circuit diagram, next to the image of the capacitor, its nominal capacitance is indicated in microfarads (μF) or picofarads (pF). When designating electrolytic and high-voltage capacitors, after the rated capacitance the value of the maximum operating voltage, measured in volts (V) or kilovolts (kV), is indicated.

Variable capacitors

To designate capacitors with variable capacitance, two parallel segments are used, which are crossed by an inclined arrow. Movable plates connected at a certain point in the circuit are depicted as a short arc. Next to it is a designation for the minimum and maximum capacity. A block of capacitors, consisting of several sections, is combined using a dashed line intersecting the adjustment signs (arrows).

The trimmer capacitor designation includes a slanted line with a dash at the end instead of an arrow. The rotor appears as a short arc. Other elements - thermal capacitors - are designated by the letters SK. In its graphic representation, a temperature symbol is placed next to the nonlinear regulation sign.

Permanent capacitors

Graphic symbols for capacitors with constant capacitance are widely used. They are depicted as two parallel segments and conclusions from the middle of each of them. The letter C is placed next to the icon, after it - the serial number of the element and, with a small interval, a numerical designation of the nominal capacity.

When using a capacitor with in a circuit, an asterisk is placed instead of its serial number. The rated voltage value is indicated only for high voltage circuits. This applies to all capacitors except electrolytic ones. The digital voltage symbol is placed after the capacity designation.

The connection of many electrolytic capacitors requires correct polarity. In the diagrams, a “+” sign or a narrow rectangle is used to indicate a positive cover. In the absence of polarity, narrow rectangles mark both plates.

Diodes and Zener diodes

Diodes are the simplest semiconductor devices that operate on the basis of an electron-hole junction known as a pn junction. The property of one-way conductivity is clearly conveyed in graphic symbols. A standard diode is depicted as a triangle, symbolizing the anode. The apex of the triangle indicates the direction of conduction and abuts the transverse line indicating the cathode. The entire image is intersected in the center by an electrical circuit line.

The letter designation VD is used. It displays not only individual elements, but also entire groups, for example, . The type of a particular diode is indicated next to its position designation.

The basic symbol is also used to designate zener diodes, which are semiconductor diodes with special properties. The cathode has a short stroke directed towards the triangle, symbolizing the anode. This stroke is positioned unchanged, regardless of the position of the zener diode icon on the circuit diagram.

Transistors

Most electronic components have only two terminals. However, elements such as transistors are equipped with three terminals. Their designs come in a variety of types, shapes and sizes. Their general principles of operation are the same, and minor differences are associated with the technical characteristics of a particular element.

Transistors are used primarily as electronic switches to turn various devices on and off. The main convenience of such devices is the ability to switch high voltages using a low voltage source.

At its core, each transistor is a semiconductor device with the help of which electrical oscillations are generated, amplified and converted. The most widespread are bipolar transistors with the same electrical conductivity of the emitter and collector.

In the diagrams they are designated by the letter code VT. The graphic image is a short dash with a line extending from the middle of it. This symbol indicates the base. Two inclined lines are drawn to its edges at an angle of 60 0, displaying the emitter and collector.

The electrical conductivity of the base depends on the direction of the emitter arrow. If it is directed towards the base, then the electrical conductivity of the emitter is p, and that of the base is n. When the arrow is directed in the opposite direction, the emitter and base change their electrical conductivity to the opposite value. Knowledge of electrical conductivity is necessary to correctly connect the transistor to the power source.

In order to make the designation on the diagrams of radio components of the transistor more clear, it is placed in a circle indicating the housing. In some cases, a metal housing is connected to one of the terminals of the element. Such a place on the diagram is displayed as a dot placed where the pin intersects with the housing symbol. If there is a separate terminal on the case, then the line indicating the terminal can be connected to a circle without a dot. Near the positional designation of the transistor its type is indicated, which can significantly increase the information content of the circuit.

Letter designations on radio component diagrams

Basic designation	Item name	Additional designation	Device type
	Device		Current regulator
			Relay block
			Device
	Converters		Speaker
			Thermal sensor
			Photocell
			Microphone
			Pickup
	Capacitors		Power capacitor bank
			Charging capacitor block
	Integrated circuits, microassemblies		IC analog
			Digital IC, logic element
	Elements are different		Thermal electric heater
			Lighting lamp
	Arresters, fuses, protective devices		Discrete instantaneous current protection element
			The same for inertial current
			fuse
			Arrester
	Generators, power supplies		Battery
			Synchronous compensator
			Generator exciter
	Indicating and signaling devices		Sound alarm device
			Indicator
			Light signaling device
			Signal board
			Signal lamp with green lens
			Signal lamp with red lens
			Signal lamp with white lens
			Ionic and semiconductor indicators
	Relays, contactors, starters		Current relay
			Indicator relay
			Electrothermal relay
			Contactor, magnetic starter
			Time relay
			Voltage relay
			Enable command relay
			Trip command relay
			Intermediate relay
	Inductors, chokes		Fluorescent lighting control
			Action time meter, clock
			Voltmeter
			Wattmeter
	Power switches and disconnectors		Automatic switch
	Resistors		Thermistor
			Potentiometer
			Measuring shunt
			Varistor
	Switching device in control, signaling and measuring circuits		Switch or switch
			Push-button switch
			Automatic switch
	Autotransformers		Current transformer
			Voltage transformers
	Converters		Modulator
			Demodulator
			power unit
			Frequency converter
	Electrovacuum and semiconductor devices		Diode, zener diode
			Electrovacuum device
			Transistor
			Thyristor
	Contact connectors		Current collector
			High frequency connector
	Mechanical devices with electromagnetic drive		Electromagnet
			Electromagnetic lock

Electronic transformers are replacing bulky steel core transformers. The electronic transformer itself, unlike the classical one, is a whole device - a voltage converter.

Such converters are used in lighting to power 12-volt halogen lamps. If you have repaired chandeliers with a remote control, then you have probably encountered them.

Here is a diagram of an electronic transformer JINDEL(model GET-03) with short circuit protection.

The main power elements of the circuit are n-p-n transistors MJE13009, which are connected according to the half-bridge circuit. They operate in antiphase at a frequency of 30 - 35 kHz. All the power supplied to the load - halogen lamps EL1...EL5 - is pumped through them. Diodes VD7 and VD8 are necessary to protect transistors V1 and V2 from reverse voltage. A symmetrical dinistor (aka diac) is necessary to start the circuit.

On transistor V3 ( 2N5551) and elements VD6, C9, R9 - R11, a short circuit protection circuit is implemented at the output ( short circuit protection).

If a short circuit occurs in the output circuit, the increased current flowing through resistor R8 will cause transistor V3 to operate. The transistor will open and block the operation of the DB3 dinistor, which starts the circuit.

Resistor R11 and electrolytic capacitor C9 prevent false operation of the protection when the lamps are turned on. When the lamps are turned on, the filaments are cold, so the converter produces a significant current at the beginning of the start-up.

To rectify the 220V mains voltage, a classic bridge circuit of 1.5-amp diodes is used 1N5399.

Inductor L2 is used as a step-down transformer. It takes up almost half the space on the converter PCB.

Due to its internal structure, it is not recommended to turn on the electronic transformer without load. Therefore, the minimum power of the connected load is 35 - 40 watts. The operating power range is usually indicated on the product body. For example, on the body of the electronic transformer in the first photo the output power range is indicated: 35 - 120 watts. Its minimum load power is 35 watts.

It is better to connect halogen lamps EL1...EL5 (load) to an electronic transformer with wires no longer than 3 meters. Since significant current flows through the connecting conductors, long wires increase the total resistance in the circuit. Therefore, lamps located further away will shine dimmer than those located closer.

It is also worth considering that the resistance of long wires contributes to their heating due to the passage of significant current.

It is also worth noting that, due to their simplicity, electronic transformers are sources of high-frequency interference in the network. Typically, a filter is placed at the input of such devices to block interference. As we can see from the diagram, electronic transformers for halogen lamps do not have such filters. But in computer power supplies, which are also assembled using a half-bridge circuit and with a more complex master oscillator, such a filter is usually mounted.

In this article, we will take a closer look at how the H-bridge works, which is used to control low-voltage DC motors. As an example, we will use the L298 integrated circuit, which is popular among robotics enthusiasts. But first, from simple to complex.

H-bridge on mechanical switches

The direction of shaft rotation of a DC motor depends on the polarity of the power supply. To change this polarity, without reconnecting the power supply, we can use 4 switches as shown in the following figure.

This type of connection is known as an "H Bridge" - due to the shape of the circuit, which looks like the letter "H". This motor connection diagram has very interesting properties, which we will describe in this article.

If we close the upper left and lower right switches, the motor will be connected on the right to negative and on the left to positive. As a result, it will rotate in one direction (the current path is indicated by red lines and arrows).

If we close the upper right and lower left switches, the motor will be connected on the right to positive, and on the left to negative. In this case, the motor will rotate in the opposite direction.

This control circuit has one significant drawback: if both switches on the left or both switches on the right are closed at the same time, the power supply will be short-circuited, so this situation must be avoided.

The interesting thing about the following circuit is that by using only the two top or bottom switches, we remove power from the motor, causing the motor to stop.

Of course, an H-bridge made entirely of derailleurs is not very versatile. We have given this example only to explain in a simple and visual way the principle of operation of the H-bridge.

But if we replace the mechanical switches with electronic keys, the design will be more interesting, since in this case the electronic keys can be activated by logic circuits, for example, a microcontroller.

Transistorized H-bridge

To create an electronic H-bridge on transistors, you can use both NPN and PNP type transistors. Field effect transistors can also be used. We will look at the NPN transistor version because this is the solution used in the L298 chip, which we will see later.

A transistor is an electronic component whose operation can be complex to describe, but in relation to our H-bridge, its operation is easy to analyze since it operates in only two states (cutoff and saturation).

We can think of a transistor simply as an electronic switch that is closed when the base (b) is 0 V and open when the base is positive.

Okay, we've replaced the mechanical switches with transistor switches. Now we need a control unit that will control our four transistors. For this we will use logical elements of the “AND” type.

H-bridge control logic

An AND gate is made up of integrated electronic components and, without knowing what's inside it, we can think of it as a kind of "black box" that has two inputs and one output. The truth table shows us 4 possible combinations of input signals and their corresponding output signal.

We see that only when both inputs have a positive signal (logical one), a logical one appears at the output. In all other cases, the output will be logical zero (0V).

In addition to this AND gate, our H-bridge will need another type of AND gate, where we can see a small circle at one of its inputs. This is still the same logical element “AND”, but with one inverting (inverted) input. In this case, the truth table will be slightly different.

If we combine these two types of "AND" elements with two electronic switches, as shown in the following figure, then the state of the "X" output can be in three states: open, positive or negative. This will depend on the logic state of the two inputs. This type of output is known as "Three-State Output" and is widely used in digital electronics.

Now let's see how our example will work. When the ENA (enable) input is 0V, regardless of the state of the A input, the X output will be open because the outputs of both the AND gates will be 0V, and hence the two switches will also be open.

When we apply voltage to the ENA input, one of the two switches will be closed depending on the signal at input "A": a high level at input "A" will connect output "X" to positive, a low level at input "A" will connect output "X" "to the minus power supply.

Thus, we built one of the two branches of the “H” bridge. Now let's move on to consider the operation of a full bridge.

Operating a complete H-bridge

By adding an identical circuit for the second branch of the H-bridge, we get a complete bridge to which the motor can already be connected.

Note that the enable input (ENA) is connected to both legs of the bridge, while the other two inputs (In1 and In2) are independent. For clarity of the circuit, we did not indicate the protective resistances at the bases of the transistors.

When ENA is 0V, then all logic gate outputs are also 0V, and therefore the transistors are closed and the motor does not rotate. If a positive signal is applied to the ENA input, and there is 0V at the IN1 and IN2 inputs, then elements “B” and “D” will be activated. In this state, both motor inputs will be grounded and the motor will also not rotate.

If we apply a positive signal to IN1, while IN2 is 0V, then logic element “A” will be activated along with element “D”, and “B” and “C” will be disabled. As a result of this, the engine will receive plus power from the transistor connected to element “A” and minus power from the transistor connected to element “D”. The motor will start rotating in one direction.

If we invert (flip) the signals at the inputs IN1 and IN2, then in this case the logic elements “C” and “B” are activated, and “A” and “D” are disabled. The result of this is that the motor will receive positive power from the transistor connected to “C” and negative power from the transistor connected to “B”. The motor will begin to rotate in the opposite direction.

If there is a positive signal at the inputs IN1 and IN2, then the active elements with the corresponding transistors will be “A” and “C”, while both motor outputs will be connected to the power supply positive.

H-bridge on driver L298

Now let's look at the operation of the L298 chip. The figure shows a block diagram of the L298 driver, which has two identical H-bridges and allows you to control two direct current (DC) motors.

As we can see, the negative part of the bridges is not directly connected to ground, but is available on pin 1 for the bridge on the left and on pin 15 for the bridge on the right. By adding a very small resistance (shunt) between these pins and ground (RSA and RSB), we can measure the current consumption of each bridge using an electronic circuit that can measure the voltage drop at the "SENS A" and "SENS B" points.

This can be useful for regulating motor current (using PWM) or simply activating a protection system in case the motor stalls (in which case its current consumption increases significantly).

Protection diode for inductive loads

Each motor contains a wire winding (coil) and, therefore, in the process of controlling the motor, a surge of self-induction EMF occurs at its terminals, which can damage the bridge transistors.

To solve this problem, you can use fast Shottky type diodes or, if our motors are not particularly powerful, just regular rectifier diodes such as 1N4007. It must be borne in mind that the bridge outputs change their polarity during motor control, so it is necessary to use four diodes instead of one.

Why do we need motor drivers and H-bridges in particular?

Having learned to “jump” pins and light up LEDs, Arduino fans and enthusiasts want something more, something more powerful, for example, learning to control motors. It is impossible to directly connect the motor to the microcontroller, since typical controller pin currents are several milliamps, and for motors, even toy ones, the count is tens and hundreds of milliamps, up to several amperes. The same thing with voltage: the microcontroller operates with voltages up to 5 V, and motors come in different voltages.

This review is only about powering brushed DC motors; for stepper motors it is better to use specialized stepper motor drivers, and brushless motors have their own drivers; they are incompatible with brushed motors. Note that in the Russian-language literature there is some terminological confusion - engine drivers are called both “hardware” modules and code fragments, functions responsible for working with these “hardware” drivers. By “driver” we mean a module that is connected on the one hand to a microcontroller (for example, to an Arduino board), and on the other hand to the motor. This “converter” of the controller’s logical signals into output voltage to power the motor is the “driver” of the motor, and, in particular, our L9110S driver.

Operating principle of doubleH-bridge basedL9110 S

H - bridge (read "ash-bridge") - an electronic module, analogous to a switch, usually used to power DC motors and stepper motors, although more specialized modules are usually used for stepper motors. It is designated “H” because the circuit diagram of an H-bridge resembles the letter H.

The “stick” H has a DC motor. If you close contacts S1 and S4, the motor will rotate in one direction, on the left there will be zero (S1), on the right + voltage (S4). If you close contacts S2 and S3, then on the right contact of the motor there will be zero (S3), and on the left + power (S1), the motor will rotate in the other direction. The bridge is an L9110 chip with protection against through currents: when switching, the contacts first open, and only after a while other contacts close. There are two L9110 chips on the board, so one board can control two DC consumers: motors, solenoids, LEDs, whatever, or one two-winding stepper motor (such stepper motors are called two-phase bipolar).

Board elements

The board is small, there are few elements:

1. Motor connection A
2. Motor connection connector B
3. Motor A H-bridge chip
4. Motor B H-bridge chip
5. Power and control connection pins

Connection

Motor A and Motor B - two outputs for connecting a load, current no more than 0.8 A; V-1A - signal “Motor B forward”; IN 1B- signal “Motor B reverse”; Ground (GND)- must be connected to the ground of the microcontroller and the motor power supply.; Nutrition (VCC) - motor power supply (no more than 12 V); A-1A - signal "Motor A forward"; A-1B-"Motor A reverse" signal. The signals on the pins control the voltage at the outputs for connecting motors:

To smoothly control the output voltage, we apply not just HIGH, but a pulse-width modulated (PWM) signal. All Arduino pins marked with ~ can give PWM output with the command analogWrite(n,P), where n is the pin number (in Arduino Nano and Uno these are 3.5-6 and 9-11, respectively). When using these pins for a PWM signal, you must use Timers 0 (pins 5 and 6), Timer 1 (pins 9 and 10) and Timer 2 (pins 3 and 11). The fact is that some library functions can use the same timers - then there will be a conflict. By and large, it is enough to know that pin 3 is connected to input A-1B, and pin 5 to input A1-A, the digitalWrite(3,127) command will supply 50% of the voltage to the motor in the forward direction.

Usage example

Robot control: trolley with headlight (white LED) and reversing light (red LED). The program is listed below and describes the cyclic movement of the cart: forward-stop-backward-stop. All important steps in the program are commented.

The motor is connected to the terminals of MOTOR A, the LEDs are connected to the output of MOTOR B. The robot moves TIME forward by turning on the white LED. Next is the TIME time with half-lit white LEDs. Then it drives back, turning on the red LEDs. Next is TIME again, turning on the red and then white LEDs at half brightness. // L9110S motor driver // by Dr.S // website // define which ports we will use to control the motor and LEDs #define FORWARD 3 #define BACK 5 #define WHITE_LIGHT 6 #define RED_LIGHT 9 #define LEDOUT 13 #define TIME 5000 unsigned char Forward_Speed ​​= 200; unsigned char Back_Speed ​​= 160; unsigned char White_Light = 210; unsigned char Red_Light = 220; void setup() ( // declare bridge control pins as outputs: pinMode(FORWARD, OUTPUT); pinMode(BACK, OUTPUT); pinMode(WHITE_LIGHT, OUTPUT); pinMode(RED_LIGHT, OUTPUT); pinMode(LEDOUT, OUTPUT); ) // the loop routine runs over and over again forever: void loop() ( // The robot moves forward for time TIME analogWrite(WHITE_LIGHT, White_Light); // Turn on the white LED "headlights" analogWrite(RED_LIGHT, 0); analogWrite (FORWARD, Forward_Speed); // The robot went forward analogWrite(BACK, 0); delay(TIME); // and wait a little // The robot turns on the “headlights” to half the normal brightness and stands analogWrite(WHITE_LIGHT, White_Light / 2); // Turn on the white LED "headlights" as parking lights analogWrite(RED_LIGHT, 0); analogWrite(FORWARD, 0); // The robot is standing analogWrite(BACK, 0); delay(TIME); // and wait a little // Robot turns on the red "reverse" LEDs and goes backwards analogWrite(WHITE_LIGHT, 0); // Turn on the white LED "headlights" as parking lights analogWrite(RED_LIGHT, Red_Light); analogWrite(FORWARD, 0); analogWrite(BACK, Back_Speed); // Robot goes back delay(TIME); // and wait a bit // The robot turns on alternately red and white LEDs and stands analogWrite(WHITE_LIGHT, 0); analogWrite(RED_LIGHT, Red_Light / 2); // Turn on the red LED as parking lights analogWrite(FORWARD, 0); analogWrite(BACK, 0); // The robot costs delay(TIME / 2); // and wait a bit analogWrite(WHITE_LIGHT, White_Light / 2); // Turn on the white LED "headlights" as parking lights analogWrite(RED_LIGHT, 0); delay(TIME / 2); // and wait a bit)

Schematic diagram

Module Specifications

• Two independent outputs, up to 800 mA each
• Maximum overload capacity 1.2 A
• Supply voltage from 2.5 to 12 V
• Logic levels compatible with 3.3 and 5 V logic
• Operating range 0 °C to 80 °C