113 hardware application notes necessary for hardware engineers

/ 2019-07-22 / News

1 Reed switch is a sensing element. When the magnet is close, the normally open contact is closed and the sense of inductance is circuit The contact load is only ten milliamps

2 usually the toy DC motor has a low operating voltage, although it can be started at 1.5~3V. However, the starting current is larger (1~2 amps), and the running current is about 500 mA when the motor is no-load

3 low-power silicon tube 8050, the maximum allowable current ICM of the collector can reach 1.5A to meet the requirements of motor starting current

4 bimetal composite Switch, closed when hot

5 usually photoresistor,For example, the MG45 has a bright resistance when light is irradiated. The 2 to 10 kΩ photoresistor is an electronic component that is rapidly increased in light-conducting conductivity. The commonly used model is MG45-1. When the working voltage is 5V, the current should not exceed 2mA.

6 water resistance is about 50kΩ

In the general case, the power frequency current below 8-10 mA, the DC current below 50 mA can be used as the safe current allowed by the human body. Under the human body resistance can be considered 1000-2000 Euros

8 low voltage (5V) buzzer, its working current only needs Ten milliamps

9relay coil (JRC-21F) operating current is about 60mA, which is smaller than the operating current of the toy motor.Ultra-small power relays commonly used for buzzer and light-emitting diodes, current model is JRC-21F, coil power supply voltage is 3V or 6V contact working DC 24V , 1A relay coil resistance from ten ohms (3 ~ 6v) ~ ten thousand ohms (220v) 24V about 1K multi-coil current does not generally exceed 100m

10 illuminate Diodes differ from ordinary diodes in that the forward voltage drop during turn-on is relatively large, typically 1.5 to 2.V (common silicon diode is about 0.7V). The operating current of the LED is generally 10~40mA

11Multimeter The diode is measured by the on-resistance of the voltage drop diode. Between 100 Euros or Thousands of Euros

12 If the tube is in the form of a common anode, then its driver stage should be a collector open circuit OC) structure,If the tube is in the form of a common cathode, its driver stage should be the emitter output or the source output circuit.

13 regulator is connected in the circuit. . The reverse voltage of the Zener diode is called the stable voltage.

The bulb resistance of the 14220V is about one kilo ohm (25 watt bulb resistance). About 2000 ohms, working voltage 220 volts) current hundred milliamps small bulb (3v-5v) resistance ten ohms current hundred milliamperes

15 car starter start Current is 200~600A

16 motor coil resistance does not exceed 2 ohms current to Baan for 380V motor 1 kW corresponds to 2 amps

17 ignition coil primary coil resistance does not exceed 1 ohms sub-about ohms

18 IC output capability output high level current

19 74LS: 400uA (cannot drive LED) (output impedance (internal resistance) 50 ~ 250 ohms (calculated according to short circuit current) The ability to carry load requires the load input resistance to be greater than 12K (400uA according to the output high level current). The input resistance of LS is 250K (20uA according to the input high level input current)))

74HC: 4mA (output impedance (internal resistance) ten ohms? (calculated according to short-circuit current), the ability to load with load requires load input resistance greater than 1.25K (according to output high level current calculation 4mA The input resistance of HC is 50M ohms (calculated according to the input high level input current.1uA)))

current 74LS: 8mA 74HC: 4mA

IC The output is equivalent to a power supply. The smaller the internal resistance of the power supply is, the stronger the relative driving capability is. The internal resistance of the power supply is less than 1 ohm. The intermediate circuit input resistance is relatively large, and the output drive stage resistance is large (light bulb, relay). Small (horn, nozzle)

For the common-transistor transistor, the input resistance is approximately Rb and the output resistance is Rc

Ejector output input impedance is large Rb+(1+B)Re Output impedance is small

20 electret microphone resistance is about 500~800 ohms output is 3 end. It integrates FET (impedance matching)

Speaker resistance 2 ohms, 4 ohms, 8 ohms, 16 ohms Headphone resistance 20 to 600 ohms

21 oscilloscope input The resistance is 1M ohm

Digital multimeter voltage input resistance 1M ohmmeasurement resistance output voltage 0.65V

diode output constant current source 1mA

22 for speakers Channels refer to channels with different frequencies. Active speakers are amplifiers combined with speakers

headphones are 3-pin left channel right channel and ground

23 sensor has electrical signal (to be enlarged and shaped) and does not generate electrical signal

24 integrated op amps from 10,000 to 100,000 so there is a short virtual input impedance so the input current is 0

25 Zener diode drive capacity does not exceed 1A

26 counter can achieve two functions, counting and frequency division.

Asynchronous counters: Slow flipping one by one.

Synchronization Counter: Flip at the same time.

BCD (decimal) counter: (0~9).

binary counter (0 to 15).

Ripple counter: Count is relatively large, 7 levels, 14 levels, 21 levels

27 triode = Transistors Logic Array=OC Gate

9013(NPN) 9012(PNP)

Max Ic 500mA

Ib is micro-level

Max Vceo 20V

8050(NPN) 8550 (PNP)

Max Ic 1.5A

Ib is milliamp level

Max Vceo 25v

2003(crystal tube array) (NPN)

Max Ic 500mA

Max Vceo 50v (just used as a switch is not used for amplification)

7407 (6 gate buffer driver OC gates)

Maximum output 40mA

Max Vceo 30v (small drive capability)

284007 Forward current 1A (rated value)

Maximum forward current 30A

Maximum reverse voltage 700V

Forward pressure drop 0.9v

For rectifier clamp protection

4148 Forward current 300mA (rated value)

Maximum forward current 2A

Maximum reverse voltage 75V

Forward pressure drop 0.7 v

for small signal occasions

LED drop voltage is 1.5~2.5V Between

LED operating current is generally 10~40mA

29 7805 maximum input voltage 35V can provide 1.5A current (typically 500mA)

30 optocoupler4N32 input rated current 60mA maximum forward current 3A reverse voltage 6v Vceo 30V Ic 150mA

31 transistors are divided into bipolar transistors and field effect transistors. The field effect transistor is divided into a junction field effect transistor JFET and an insulated gate field effect transistor.

Field effect transistor input resistance is large, output resistance is small

32 negative feedback: from the back The collector of the stage amplifier samples the voltage feedback

the current is sampled from the emitter of the post amplifier

Feedback signal is connected to the base of the transistor is parallel feedback

Feedback signal is connected to the transistor emitter is serial feedback

Parallel negative feedback reduces input resistance

Incremental negative feedback input resistance increases

Voltage negative feedback reduces output resistance

Current negative feedback increases output resistance

33Differential Amplifier has the advantage over direct cascade amplifiers: suppresses temperature drift. The greater the Re, the better the temperature drift is

Constant current source is equivalent to a large resistance

34 integrated op amp amplification is too large, in order to increase the input range, it must be connected to feedback form. 

35 shot-level output and output efficiency is only about 20%

Push-pull output output efficiency Up to 80%

Double power supply: output without capacitor

Single power supply: output plus capacitor.

Set successfully put LM384, 8W power output can be connected to 500 microfarad capacitors. p>

36 inverse proportional operation:Voltage Parallel Negative Feedback Magnification -R2/R1 Input Impedance R1 Output Impedance is small

Double proportional operation: voltage series negative feedback amplification factor 1+R2/R1 Large output impedance Small output impedance

Voltage follower: Like the emitter follower, the input impedance is large and the output impedance is small. Uo=Ui

37 can use an amplifier to form an active filter, a voltage source, and a current source.

38 op amp with negative feedback, the op amp works in the linear region active filter, voltage source, current source

Operation has positive feedback,The op amp operates in a non-linear region. Limiter Voltage Comparator (no feedback) Zero-crossing comparator Hysteresis comparator (positive feedback) Precision shaping circuit (feedback loop plus diode) waveform generation circuit.

39 power rectification-filtering-regulation 78 series: the input and output voltage difference must not be lower than 3V

40 8051 generally refers to the 89c51 produced by intel company, which refers to the 51 series products produced by Atmel company

41 Microcontroller reset circuit: use a 10u capacitor and 10K resistor to complete the addition of a 1N448. Reset time is not less than 5ms or 22u capacitor 1K resistor High reset: Capacitor is close to the power supply. Low level reset: The capacitor is close to ground.

42 51 MCU addressing mode: immediate, direct, register ( Registers are faster than direct, direct and register are equivalent to put the data into a ram variable), indirect addressing (the address is placed in the variable, equivalent to the pointer in c++, in the inter-address In the address, only R0 or R1 can be used to store the searched data, etc. (R register can be used as a register to control the number of loops)), indexed addressing (for table lookup MOVC A, @A+DPTR) MOV DPTR,# TABLE (the meaning of the # in front of the label: the label is an address!! For example, TABLE is 100H #TABLE is the immediate number #100)

DP1 is a DPTR is a A 16-bit register that stores the address.Access to the external ram must use the A accumulator

44 SP should be initialized before use to indicate where the stack segment starts. For example, MOV SP, #5FH ORG indicates where the program segment is from Start.

45 shift command can be used for the lantern test.


AJMP is a two-byte instruction LJMP is three bytes Command,

47 CJNE: Compare two numbers after they are unequal and transfer (first judge whether they are equal, then you can judge whether it is big or small with JC jump) DJNZ : After subtracting 1 is not equal to zero transfer, it is used to control the transfer instruction commonly used in the loop number bit operation:JB (transfer when bit is 1) JBC (bit is 1 transfer and cleared to 0 for query mode clear interrupt flag, no need to manually clear 0 when using interrupt mode)

48 When performing bit processing, CY (that is, the carry bit) is called "bit accumulator" which is equivalent to A in byte processing.

49 counter/timer There are a number of restrictions to run: 1. C/T switch 2. Tr switch 3. Gate switch (Gate=1, it is also controlled by Int1). Start T with SETB TR0. There are 4 ways of working: 0. 13 bits 1. 16 bits 2. There are presets (high 8 bits for preset, low 8 bits for counting, so the range is small), generally used for baud rate generator 3. Timer 0 is divided into two independent timers/counters. Generally, when T1 works in mode 2, T0 works in mode 3. Registers for T: TCON Control Timers and Interrupts TMOD is primarily used to control how T operates.

The work done in the interrupt when the timer is used in the interrupt mode: 1. Action 2 to be implemented after the interruption. Re-preset the counter (equivalent to the work done automatically by mode 2). Set a soft count loop operation, output after multiple timings, which increases the timing time.

50 Registers for Interrupts: IE: Interrupt Master Switch IP: Interrupt Priority ECON SCON

Interrupt program time can't be greater than interrupt interval

51 communication direction: In serial communication, the communication interface can only be used The one-way transmission method of sending or receiving is called simplex transmission; and the two-way transmission of data between the two machines is called duplex transmission. In the duplex transmission mode, it is divided into half-duplex transmission and full-duplex transmission. Half-duplex transmission is not possible to send and receive at the same time between two machines, any time,Can only send or receive information.

52 serial port: mode 1: shift register mode Externally connected to a parallel shift register CD4094 74LS164, you can expand a parallel port

53 software removes the button jitter and finds that it is pressed again 10ms after the button is pressed.

54 The value of the program counter (PC) in the 8051 after power-on reset is '0000', so the program always starts from the '0000' unit.

55 carbon film resistor:

power is 1/6, 1/4W


Accuracy 5%

Cheap 1~2 cents

Precision Resistor

Power is 1/6, 1/4W


High precision 1%

5 cents

oxide film resistance:



Accuracy 5%

5 cents

Cement resistance:



Accuracy 5%

Less than 1 yuan

Ceramic resistor:



accuracy 5%

tens of dollars

2W High Voltage Resistor


Accuracy 5%

5 yuan


accuracy 5 %

less than 1 yuan

exclusion (5 feet-12 feet)


Accuracy 5%

5 points/foot

adjustable resistance (sleeping. vertical)


accuracy 5%

less than 1 yuan

Small power resistors are generally selected as precision resistors because they are inexpensive.

General press Power selection resistance: 1 ~ 2W oxide film resistance 5 ~ 50W cement resistance 50 ~ 200W ceramic resistance (too expensive)

56 Capacitance:

Ceramic capacitor: 0.5p~0.1u Withstand voltage up to 30KV is generally 50V

Polyester capacitor: 100p~4.4u The withstand voltage is generally 50~100V, the highest is 630V

Electrolytic capacitor: 0.1u~220,000u Etc.

6.3v 10v 16v 25v 35v 50v 160v 250v 400v (no 15,20)

The pressure is over 100v, which is very expensive even a few hundred dollars

capacitance: 0.1u~100u withstand voltage up to 50V similar electrolytic capacitor

monolithic capacitor: 10p~2u withstand voltage generally 50~100V

Safety for communication 250V 0.01u~2.2u

Resin for AC 250V 0.1u~47u

The smaller the capacitance, the higher the pressure resistance: the size of the ceramic tile

57 diode :

Rectifier: 1N40 Series (1A) 1N54 Series (3A) 1N52 6A Series (6A)


Fast recovery: FR series (1A ~ 6A) FR10 * (1A) FR15 * (1.5A) FR20 * (2A) FR30 * () 3A FR60 *(5A)

very cheap no more than 5 horns

siliconrectifier Bridge from 1A to 40A withstand voltage 100V ~ 1000V no more than 10 yuan

Zener diode: 2CW 2DW

58 triode: too many models 2N (Japan, USA) B×× (Europe).

Small and medium power (less than 1W current less than 1A voltage generally does not exceed 100V): 90 series 8050 8550 in the country half (power is slightly derived from 90) 2SC1815 2SC945

2N5400 2N5550 (higher voltage resistance than 100V)

The power in the middle is relatively small (1~1.5W voltage is higher than 200V and the current does not exceed 0.5A) ). Used in color TV cameras.

High power (5W or more) low withstand voltage (less than 100V current 10A or more): 2N3050 MJM2955 (for power supply Expansion)

very little pressure in the medium

high withstand voltage (several hundred volts) , current 2A or more):For color TV and display

2SD820 2SD1403 (for power supply) 2SD951 (for line output)

Power supply: 78, 79 series (fixed output, maximum input voltage 35V output 5V ~ 24V)

LM317 LM337 (output voltage adjustable 1.25 ~ 37V can provide 1.5V current, input and output difference can not be greater than 40V) LM350 (3A)

TL431 The three-terminal adjustable reference source is used because the output power is too small

59 optocoupler:4N TLP PC MOC

60 Dial switch: Generally used in microcontrollers to set initial parameters and not change frequently. The switch is usually directly connected to the ground, and there is a pull-up resistor. When there is a pull-up resistor inside the microcontroller, it is omitted (p1.p2.p3 is a quasi-bidirectional port, and when input, it is internally up to a high level)

XLF: Micro Printer.

Integrated Infrared Receiver: Integrates infrared reception and amplification, and can receive infrared light without any external components. The output is compatible with the TTL level signal

DM-162 Liquid Display module can be directly connected to the microcontroller.

ARP9600: Voice Recording and Playback Chip.

UPC1651 High Gain High Frequency Amplification Integrated Circuit for Audio Signal can be directly connected to the wire

MOC3041: optocoupler, bidirectional thyristor

97A6: SCR

TWH8778(8751): Power fast, working voltage 3~24V, switching current 1A. Input

TTL compatible, can replace conventional relays

LM324: four integrated op amps

HT7150: Power regulator maximum input voltage 24V output is 5V output current is only 30mA

LA4425: Amplifier can drive 8 ohm 5W speakers. LM384 TDA2030 can Drive 8 ohm 12W speaker LM386

LM1875 TDA1514 TDA1521 (high power)

61 LED The digital tube display is very simple:

1 first convert the hexadecimal to decimal, put it in a, b

2 display code (no decoding circuit)

3 Output from the output port

4 open control bits

5 delay

6 off control bits

62 MCU direct drive 8050 is driven with low level.< /p>

63 The rated power of the resistor is generally the maximum power, which is much less than this power when used. The power of other devices refers to the rated power, and the device should be near its rated power. Work.

Insufficient drive capability has two situations:

1. Input resistance of the device Too small, the output waveform will be distorted.If the TTL level does not drive the relay

2. The input resistance of the device is large enough, but it does not reach the power of the device. For example, a low-power amplifier can drive a high-powered speaker, and the speaker can sound, but the volume is small, but the output voltage is not large enough.

64 analog integrated circuits can be divided into four types: linear, nonlinear, power, and microwave (frequency over 300MHz).

65 famous chip manufacturers:

Japan: NEC (Japan)

HITACHI (Hitachi)









JRC (JRC Series)


United States:



NATIONAL SEMICONDUCTOR (the national half logo is an F or a water wave)

TI (Dexus Instruments produces TL series)

SIGNETICS (Signetix production NE555 NE series)

HARRIS (Harris is RCA (CA series)

GE INTERSIL three in one (production of ICL ICM series chips))< /p>

AD-PMI (Audio Devices AD OP DG ADG Series)


SPRAGUA (Sprager produces ULN series)

IR (International Rectifier Corporation)

LT (LINAR TECHNOLOGY production LT series) RATHEON (Raytheon production RC series)

CYPRESS SEMICONDUCTOR (icon is a cypress tree)










Taiwan: UMC

6674, 40 series are interchangeable. indicates ROM 27 EPROM 28E2PROM

67 Universal Op Amps: LM741, LM833, LM324,LF411, LF347, LF358, TL071, TL081, MC34081, MC34071, MC33078, RC4558, RC4560, NE5532, AD711

68 comparator: analog to digital, And the output is TTL compatible. LM311, LM339 (239, 139), LM319

69 multiplier: can form low-pass filter, frequency conversion, lifetime measurement . . . . AD538

Use DRAM on 70PC (model number starts with 4, such as 4164) SRAM (for 62, 65, 66,67 HM Hitachi's Memory HY Hyundai GM Venus) EPROM has a small window (starting with 27) E2PROM (starting with 29)

flash ROM: fast access speed, power off

71 power supply: single-chip power supply type: fixed: 78 79 series adjustable: LM337

Regulator ASIC: no power module, good stability, output voltage configuration LM723

Switching by means of switching: TL494 SG3524

Reference source: The output current is small,The reference voltage as AD is very high. AD580 LM113/313

72 analog switch: small signal switch, not high current switch 4066 in the 40 series AD75&times;&times;(performance is too expensive, no need)

73V/F F/V widely used in the radio field phase-locked loop In the use of communication circuits, the application is complex.

74 Driver Array: ULN2003 (Sprager)

75 A/DD/ A (ADCDAC series is produced in the country) AD574(A/D) AD7520(D/A)

Sampling holder: LF198/298/398

76 PIC MCU is a single-chip computer produced by General Instrument Company

77 Optocoupler: Toshiba's TIL Series Motorola's MOC Series Recognized only a dozen of 4N series.

78 multi-turn (single circle) potentiometer: Mexico's BOVREN brand 3006, 3296 power does not exceed 1W resistance value 10 ohms ~ 5M ohms

79 Zinc Oxide Varistor: Suppresses surge voltage, protection circuit.

80 thyristor compared to the triode:The magnification is high, reaching tens of thousands of power, and it can reach several tens of amps and several thousand volts.

81 Digital Tube Popular EDTECH Products Models start with LA LC LD LE LM LN and BSR BSG Series

82 home appliance chip:

European: DTA series

Toshiba : TA

Panasonic: AN



Hitachi: HA HM

Toyo Electric:BA




Samsung: KA

83 Digital Multimeter: 3 and a half Can oscilloscope: double trace 20M can

logic analyzer: there are many channels for digital circuits, very little use

Signal generator: High frequency up to 2MHz

Frequency meter: Special measurement frequency Unless the frequency is often measured

Sweeper: Measuring the frequency characteristic of the device

Graphic: Measuring the transistor characteristic curve because the triode quality is becoming more stable Not very useful

Power meter, field strength meter, spectrum analyzer: very specialized instrument

Switching power supply is compared with ordinary power supply: small size, cheap, but anti-interference difference ripple is large.

84 general transport Put (such as LM324,Applications requiring +-power)

1. The amplification of the signal can be used as a feedback form instead of a triode. The operational form is

2. Signal multi-channel assignment, connected to the emitter follow-up form, the input impedance is large

3. Bandpass filter for use in audio equipment, select different frequencies and process them

4. Comparator, the op amp does not connect to the feedback resistor. The application of the comparator: can be made into a voltage over limit indication.

5. Monostable trigger: In fact, the capacitor is connected to the comparator form

85 comparator (LM339) application: LM39 output It is an OC gate and needs to be pulled.

LM339 is mainly used for threshold indication, alarm, etc. The LM339 plus positive feedback forms a hysteresis comparator. It is also possible to form an oscillator.

4060 is the count/divider/oscillator. 6-inverter 4069 can be used as a square wave generator

4047 Oscillator

4033 Decimal Count/7-segment Decoder Input Pulse Output Coding Need to Add Driver

4544 BCD-7 segment decoding/driver input is 4-bit BCD code output is 7-segment code

4518 Two 4-digit BCD code counters Input is a BCD code with a 4-bit pulse output

4017 The counter/divider input is a pulse output of 10 channels. One pulse per channel

86 Using the temperature coefficient of the triode, it can be made into a temperature probe, and the triode is connected in a diode form with both the base and the collector. Together with the triode can be 3DG6

87 design power is not very large power supply: transformer select 220/15 (18), current 1.5 A (3A determines the power of the power supply)

Available off-the-shelf rectifier bridges (see capacity 5A is enough) or build with 4 diodes

Filter capacitor is a few thousand u

Regulator circuit: After filtering, use 7805 to generate your own voltage 5V. Some use LM337 to make adjustable current. Not big enough, you can add a triode to expand 2N3055

88 Y992: DC power supply, can output waveform with adjustable duty cycle, need to add crystal oscillator, drive ability is not big 10mA can be made into waveform generator, oscillator. It can be made into square wave generator with 6 inverter 4069

89 ICL7660, MAX870, MAX828 can change +5V成-5V

ICL7107 3 and a half AD for digital heads with LEDs

90 varactor diode (several hundred picofarads) varactor diode for radio channel selection.

91 infrared remote control: transmitter: 1 Encoder 2 Oscillator 3 Infrared Emitter

Receiver 1 Decoder 2 Infrared Receiver.

92LM35D integrated temperature sensor It is to make the temperature measurement sensor and the amplification circuit in one step

93 power supply design filter capacitor size selection, generally around 1A in 2000 ~ 3000u

hardware engineer necessary 113 hardware application notes

94 integrated temperature sensor, typical The products are AD590, AD592, TMP17, LM135

95 triode driver is to drive the device directly to the collector (NPN), the driving ability is affected by the transistor Ic Adding a resistor to the collector and then outputting the drive, the drive capability is affected by the resistance.

The base and collector of the triode can be voltage-transformed with different voltages. >

The emitter follows the output output voltage is less than the input control pulse output voltage is affected by the input but the driving ability is strong

96 for the NPN tube emission junction cut-off transistor cut-off

Emission junction conduction positive bias collector junction reverse bias transistor amplification

Emission junction The positive bias collector is positively biased. The voltage at the saturation output point of the triode is not fixed. The output voltage is very low.

0 Therefore, the collector junction is positively biased. When saturated, Vce has a small output maximum voltage of Vc

1 emitter-received form, the emitter junction is positively biased, and the output is reversed. The voltage is Vb

This connection is not used as a switch driver as an output to increase the drive capability and cannot be level-shifted.

2 If the emitter and collector are connected to a resistor The output point is at the collector output. When the transistor is turned off, the output Vc has an input signal. The output voltage of the transistor is Vb-0.7-Vb*(Rb/(Rb+rb+(1+β)Re)), Re is not very small. In case, the output is smaller than Vc and it is impossible to output 0 level. Therefore, this connection cannot be used as a switch

In the case of NPN, the general Rb is generally larger than Rc. Re

3 General connection collector plus a resistor (resistance can be replaced by a drive device) as a switch form.

97Protel design is divided into 3 parts:Schematic, generate netlist, generate PCB

98 bipolar transistor is a current control device. Field effect transistor is a voltage control device divided into MOSFET(insulated gate) JFET (junction)

991 degree=1kWh 1 kW (power)=1.36 horsepower

Single-phase AC for electric lamps and household appliances

Motors of the same capacity Three-phase smaller than single-phase volume < /p>

100 voltage is higher than 60V. The test pencil is lit. The test pencil is not lit. The ground line is not lit.

The two poles of the tube are bright. The tube is only DC.When there are two bulbs at both ends of the manifold, the end of the cathode is connected to the negative pole.

Megohmmeter is used to measure large resistance


113 Hardware Application Notes for Hardware Engineers

102CD4001 or Non-door use:

1 can form a RS trigger (if there is no 4043):When s is 1, the output 1 s changes back to 0. The output does not change. In this case, r input 1 is required to reset.

2 can form a harmonic oscillator with less precision

103 For audio signals, the initial small is only 5mV, amplified by the preamplifier to 500mV, and finally passed through the power amplifier output.

104 Electronic tube is made by solid heating to release the electron principle

105 roughly estimate that for a device with an input impedance of 10K, 0.1u can filter out waves above 1000HZ. 10u can filter out waves above 10HZ

106 for the triode 9013 for amplifying the input signal voltage for the mv level current uA level output signal voltage about 1V output current mA level

voltage, current Magnification is about 100 Power amplification is about 10000

107 low frequency signal refers to signals from a few Hz to a dozen KHz

108 two capacitors and two diodes can constitute a voltage doubler circuit

109 oscillation signal is generated by positive feedback LC oscillator circuit < u>RF signal RC oscillator circuit produces audio signal The crystal oscillator circuit generates oscillation through the piezoelectric effect of the crystal.

Multivibrator :An oscillator capable of outputting multiple harmonic signals

110 DTL means that the IC is composed of a diode and a triode. The TTL is that the IC consists only of a triode.

111 Process control refers to the control quantity is pressure, liquid level, flow rate, temperature, etc. The object of servo control is position.

112 Zener diodes have an inverted breakdown voltage (stable voltage) of less than 40V compared to conventional diodes and have a relatively small change in inverting dynamic resistance. 

When the 113 triode is used for amplification, Rb/Rc is slightly smaller than the current amplification factor β

The base must be connected to a resistor. Otherwise, the input resistance of the triode is equivalent to 0 when two diodes are connected. The first Rc should be one tenth of the second Rb.In this way, the waveform will not be deformed.

The base can be connected without a resistor. In this case, the first stage must have a pull-up resistor, which results in the previous level. The collector output is always 0. When the previous stage outputs 0, the current flows from the previous stage. When the previous stage is high, the current flows from the back, and the rear transistor is turned on, but it is not convenient to measure the observed waveform. It is recommended to add a resistor to the base, and the resistance is better than the Rc of the previous stage, which is convenient for observing the waveform with an oscilloscope.

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