Basic knowledge of bread board

One, what is "bread board"?
1. Structure of bread plate
The breadboard is the "Integrated Circuit Experimental Board", which is a plug-in board, which has several small "sockets (holes)" on the board. In the circuit experiment, can according to the circuit connection request, in the corresponding holes inserts the electronic component's pin and the wire and so on, causes it to contact with the hole inside the elastic contact Reed, thus joins the necessary experimental circuit. Figure 1 is a SYB-118 type bread PLATE:
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is 4 rows and 59 columns, each metal reed has 5 jacks, so the wire inserted in the 5 holes is connected by a metal reed. The reeds are electrically insulated from each other. The distance between the jacks and the reeds is the same as the standard pitch 2.54mm for the dual-inline (DIP) integrated circuit pins, and is therefore suitable for inserting various digital integrated circuits.
2. Precautions for use of bread sheets
Insert the inside hole of the breadboard pin or conductor the copper core diameter is 0.4~0.6mm, which is slightly thinner than the diameter of the pin. The component pin or the wire head to be inserted in the square hole perpendicular to the plate surface of the bread plate, should be able to feel a slight, uniform friction resistance, when the bread plate upside down, the component should be able to be clamped by the reed without falling off. The breadboard should be stored in a ventilated, dry place, especially to avoid being corroded by the electrolyte that is leaking from the battery. To keep the breadboard clean, the welded components are not inserted on the breadboard.
3. Bread Plate Test Set material
The electronic control circuit basic experiment uses the component including: the Battery Pack 2 group (3V, 6V, with the battery card, the electrode lead). Bread Plate (SYB-130 or 118, SYB-46 type). Resistor 27 only (47ω, 100Ω, 390ωx8, 1kωx6, 2.2kωx5, 3.3kω, 10kΩ, 15kω, 47kω, 330kω, 2.2mω), miniature straight-slip potentiometer (47kω), capacitor 7 (1000pF, 0.022μf, 47μf , 100ΜFX2,220ΜFX2). Photosensitive resistor (mg45-1), photodiode, switching diode (1N4148), led 4 (red, green, yellow, orange), transistor 4 (8050, 9013x2, 9014), Digital tube (LC5011). 10 Blocks of digital integrated circuits (74ls00, 74LS02, 74ls04, 74ls08, 74ls32, 74ls73, 74ls74, 74ls86, 4511, 4518). Relay (jrc-21f), bimetal Duplex (starter), magnetron switch 1 sets (bar magnet, reed switch), piezoelectric ceramic (φ27mm, with resonant shell), electronic buzzer (3V or 6V), small electric lamp 1 (3.8V), Toy DC motor (3V, with small propeller). Button Switch 2, a number of wire and the component tray. In addition, you need to prepare commonly used tools, such as tweezers, peach-shaped pliers and a small screwdriver, optional experiments need to add some of the components.
Introduction to the experiment of bread plate
Experiment is the bridge to the success of science, it is precisely because the experiment created the 19th century greatest experimental physicist, experiment Master M. Faraday, laid the foundation for the development of modern physics. After understanding the structure of the breadboard, the use of the Breadboard circuit lap experiment to understand how it is used.
1. Power-saving indicator circuit
Figure 2 is a power-saving indicator circuit:
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It consists of battery pack GB (6V), pushbutton switch SB, current-limiting resistor R (390ω), red light emitting diode and wire. The battery pack is made in series with 4 cell 5th batteries, the switch selects the bell button switch, the wiring with 1 core wire, the resistor four color ring is orange, white, brown and gold, the nominal resistance is 390ω, tolerance ±5%. The LEDs use a red light emitting diode with a diameter of 3mm. When the current-limiting resistor R is 390ω, the light in the LED is about 10mA and the brightness is already high. such as high-brightness light-emitting diodes, current-limiting resistors can be increased appropriately (1k~3.9kω), the operating currents of only 1~3ma, become a veritable power-saving indicator circuit.
Looks like Figure 2 the power-saving indicator circuit is very simple, lap circuit on the breadboard is a new attempt, need to master the method of connecting the circuit on the bread board, understand the use of resistors and light-emitting diodes, take the first step of the Breadboard circuit experiment. It is recommended that beginners use the SYB-46-type bread plate, as shown in Figure 3 to demonstrate the connection method. A common mistake is to cause a short circuit in the 5 square holes of the resistor, the two pins of the light-emitting diode in the same column, or the LEDs ' positive and negative pole pins.
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In the initial grasp of the power-saving indicator circuit breadboard connection, it is advisable to concatenate a light-emitting diode in the circuit, connected to Figure 4, Figure 5 shows two different series methods. Note: The difference between the two circuits!
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Figure 6 is a parallel circuit, it can be seen as a two-way power-saving indicator circuit, but only a common resistor.
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When connecting the parallel circuit on the bread board, the power-saving indicator circuit is illuminated after connecting, then the second way is connected as shown in Figure 7.
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It is characterized by the compact connection of each component, saving the floor area of the bread board, which has practical significance when the mating components are more. If each light-emitting diode is connected in series with a resistor, especially a light emitting diode with different luminous colors, the two LEDs will not contain each other. If the light-emitting diode series of switches, resistors in exchange for each other position, can be connected to the corresponding circuit, indicating that the bread Board circuit overlap method has been initially mastered. We should attach importance to the cultivation of skills in the process of experimental operation, not just to get the results of experimental phenomena.
2. Code Simulator
Code is a symbolic symbol used to transmit letters, numbers, punctuation, etc. in telegraph communication. In 1838, American scientist S. Morse invented the code, which is a combination of dots and two symbols, which is a widely used Morse code in Telegraph communication. In 1844, the construction of a communication line began to telegraph, unlocking a new chapter in the history of human communication.
The circuit shown in Figure 8 is a simple simulator for sending and receiving code:
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It is divided into the left and right two independent of the button switch with a buzzer. Lap the left side of the buzzer circuit on a breadboard. Note the positive sign on the side of the buzzer, the pin on the corresponding side (long pin) is the positive, and when the buzzer is plugged in, the positive polarity is connected with the positive power supply. Then use another piece of bread board to lap the right circuit, and finally two pieces of bread on the top x long reed wire connected together, the most downward y-bar link up, forming a communication line, to carry out the code to send and receive newspaper practice. Through the Code simulator Experiment, on the bread board on the "Sound and Light buzzer", familiar with the parallel circuit, understand the International Code table and telegraph communication, enhance the interest of bread Board experiment.
The attached table is a digital pronunciation and code symbol.
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1~9 and 0 of these 10 numbers are "short code" or "Long Code" of the code symbol to pass, and these code symbols are by the point "·" and zoned "-" to compose. "·" in the Code table Read as "the" (DI), read the pronunciation should be short crisp, "-" mouth read as "Up" (Dá), read to be uniform and smooth. When the Code transmitter button (push button switch) is practiced, the key time is short to produce "·" The code signal, the buzzer issued a short crisp "" sound, the button long, produce loud "-" continuous sound. Usually the "-" sound Time is "·" 3 times times the audible time, "·" and "-" or "-" and "•" The intermittent time between is a "·" The audible time. Set aside 3 "·" Between two digital code signals Do not press locking intermittent time, that is, a "-" intermittent time, to distinguish between two digital code, a group of code and another set of code between the intermittent time of 5 "·" Uninterrupted audible time. When party A sends out the code signal of its birthday date, Party B interprets the birthday date of party A according to the code signal received and completes the code receiving and dispatching exercise.
3. Charging and discharging function of capacitor
In 1745, the Dutch Leiden University, p. Musembrock, invented the "Leiden bottle", the most primitive capacitor in which a metal foil is affixed inside and outside a glass bottle as a plate pole, which forms a capacitor that is close to each other by two metal plates and insulated with a glass dielectric. As the name implies, the most important characteristic of a capacitor is the ability to store charges, charge and discharge, and to block direct current and allow AC power to pass through. The charging and discharging circuit of the capacitor shown in Figure 9 is used to understand the use of the capacitor, the phenomenon of charging and discharging of the capacitor, the influence of the time constant of the test timing resistor and the capacitor on the charging and discharging of the capacitor.
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In the experimental circuit in Figure 9, the capacitor C1 (220μf) and the C2 (220μf) are in parallel, and the total capacitance equals the sum of the capacitance of two capacitors (440μf). The left side of the circuit by the power supply GB, button switch SB1, resistor R1 and shunt capacitor C1, C2 composed of RC (resistance capacitance) charging circuit, charging current by the red light emitting diode luminous intensity display. When the SB1 is plugged in, the red LEDs Flash once. The higher the resistor value of the R1, the smaller the instantaneous current (maximum current) of the red led, the longer the charge to the capacitor. In the process of charging the capacitor, the change in charge current and voltage is shown in Figure 10.
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In Figure 9 Circuit, the right is the capacitor discharge circuit, composed of SB2, R2, green light emitting diode and shunt capacitor C1, C2. When the C1, C2 sufficient power, disconnect the SB1, the capacitor C1, C2 and the power supply GB off, then press SB2, the green light emitting diode flashing phenomenon, which is due to the capacitor C1, C2 storage charge discharge, indicating that the capacitor can store charge. When the capacitor discharges, as the charge of the capacitor is decreasing, the voltage at both ends decreases sharply, and the discharge current decreases exponentially, the voltage and discharge current of the capacitor are changed with the same as the change of charge current in Figure 10. Obviously, the resistor value of resistor R is the product of the capacitance of the charge capacitor C R. The larger the C, the longer it takes to charge and discharge, so the R. C is called the time constant of the capacitance-discharge circuit, denoted by the Greek letter tau, namely
Τ=r C
When the resistor is in ohms and the capacitance is Faraday, TAU's unit is seconds. In the circuit in Figure 9, r=1kω,c=440μf, τ=1x103x440x10-6=0.44 (seconds). In the experiment, why the light-emitting diode can only blink instantaneously, by calculating the time constant tau can be proved.
Capacitor charging and discharging circuit breadboard connection schematic See Figure 11:
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Connect in the lower left corner of the breadboard. The capacitor chooses the small electrolytic capacitor which the working voltage 10~16v, because of its large volume, must leave a certain space on the bread board, and needs a wire to connect two capacitors ' positive pole in parallel. Electrolytic capacitors in use should pay attention to polarity, long lead is positive, short pin is negative, usually the capacitor shell negative pin side has a "-" sign.

Basic knowledge of bread board