Transistors MP39, MP40, MP41, MP42.
Transistors MP39, MP40, MP41, MP42- germanium, low-power low-frequency amplification, p-n-p structures.
Metal-glass case with flexible leads. Weight - about 2 g. Alphanumeric markings on the side surface of the case.
There are the following foreign analogues:
MP39 -2N1413
MP40 - 2N104
MP41 possible analogue - 2N44A
MP42 possible analogue - 2SB288
The most important parameters.
Current transfer coefficient
for transistors MP39 rarely exceeds 12
, for MP39B it ranges from 20
to 60
.
For transistors MP40, MP40A - from 20
to 40
.
For MP41 transistors - from 30
to 60
, MP41A - from 50
to 100
.
for transistors MP42 - from 20
to 35
, MP42A - from 30
to 50
, MP42B - from 45
to 100
.
Maximum collector-emitter voltage.
For transistors MP39, MP40 - 15
V.
For MP40A transistors - 30
V.
For transistor MP41, MP41A, MP42, MP42A, MP42B - 15
V.
Limit frequency of current transfer coefficient
(fh21e) transistor for circuits with a common emitter:
To 0,5
MHz for transistors MP39, MP39A.
To 1
MHz for transistors MP40, MP40A, MP41, MP42B.
To 1,5
MHz for MP42A transistors.
To 2
MHz for MP42 transistors.
Maximum collector current. - 20 mA constant, 150 mA - pulsating.
Reverse collector current at collector-base voltage 5V and temperature environment from -60 to +25 Celsius no more - 15 μA.
Emitter reverse current at an emitter-base voltage of 5V and an ambient temperature of up to +25 Celsius no more - 30 μA.
Collector junction capacitance at a collector-base voltage of 5V at a frequency of 1 MHz - no more 60 pF.
Self-noise factor - for MP39B with a collector-base voltage of 1.5 V and an emitter current of 0.5 mA at a frequency of 1 KHz - no more 12 db.
Collector power dissipation.
For MP39, MP40, MP41 - 150
mW
MP42 has - 200
mW
Once upon a time, transistors of this series were included in widely used radio construction kits for beginners. MP39-MP42, with their rather large dimensions, long flexible leads and simple pinout, were ideal for this. In addition, a fairly large reverse current allowed them to operate in a common emitter circuit, without additional bias. Those. - the simplest amplifier was actually assembled, on one transistor, without resistors. This made it possible to significantly simplify the circuits at the initial stages of design.
Pinout of transistor MP41
Designation of transistor MP41 on diagrams
On circuit diagrams, the transistor is designated both by a letter code and by a conventional graphic code. Letter code consists of Latin letters VT and numbers ( serial number on the diagram). The conventional graphic designation of the MP41 transistor is usually placed in a circle, symbolizing its body. A short dash with a line from the middle symbolizes the base, two inclined lines drawn to its edges at an angle of 60° symbolize the emitter and collector. The emitter has an arrow pointing towards the base.
Characteristics of transistor MP41
- Structure p-n-p
- 15* (10k) V
- 20 (150*) mA
- 0.15 W
- 30...60 (5 V; 1 mA)
- Reverse collector current
- >1* MHz
- Structure p-n-p
- Maximum permissible (pulse) collector-base voltage 15* (Zk) V
- Maximum permissible constant (pulse) collector current 150* mA
- Maximum permissible continuous power dissipation of the collector without heat sink (with heat sink) 0.2 W
- Static current transfer coefficient of a bipolar transistor in a common emitter circuit 20...35* (1 V; 10 mA)
- Reverse collector current - µA
- Cutoff frequency of current transfer coefficient in a circuit with a common emitter >2* MHz
MP42 transistor pinout
Designation of transistor MP42 on diagrams
On circuit diagrams, the transistor is designated both by a letter code and by a conventional graphic code. The alphabetic code consists of the Latin letters VT and a number (ordinal number on the diagram). The conventional graphic designation of the MP42 transistor is usually placed in a circle, symbolizing its body. A short dash with a line from the middle symbolizes the base, two inclined lines drawn to its edges at an angle of 60° symbolize the emitter and collector. The emitter has an arrow pointing towards the base.
Characteristics of transistor MP42
- Structure p-n-p
- Maximum permissible (pulse) collector-base voltage 15* (Zk) V
- Maximum permissible constant (pulse) collector current 150* mA
- Maximum permissible continuous power dissipation of the collector without heat sink (with heat sink) 0.2 W
- Static current transfer coefficient of a bipolar transistor in a common emitter circuit 20...35* (1 V; 10 mA)
- Reverse collector current - µA
- Cutoff frequency of current transfer coefficient in a circuit with a common emitter >2* MHz
Low-frequency power amplifier based on germanium transistors P213, the circuit diagram of which is shown in Fig. 1, can be used to play back recordings, as a low-frequency part of the receiver (from Gn3, Gn4 sockets), as well as to amplify signals from adapted sensors musical instruments(from nests Gn1, Gn2).
- The sensitivity of the amplifier from the GnI, Gn2 sockets is 20 mV, from the Gn3, Gn4 sockets - no worse than 250 mV;
- Output power at 6.5 ohm load -2 W;
- nonlinear distortion factor - 3%;
- Reproducible frequency band 60-12,000 Hz;
- In silent mode, the amplifier consumes a current of about 8 mA, and in maximum power mode - 210 mA.
- The amplifier can be powered either from batteries or from an AC mains voltage of 127 or 220 V.
Schematic diagram
As can be seen from schematic diagram, the first amplification stage is assembled on a low-noise transistor MP39B (T1) according to a common-emitter circuit. The amplified signal is fed to potentiometer R1, from the motor of which, through resistor R2 and separating capacitor C1, the low-frequency signal reaches the base of the transistor. The load of the first stage of the amplifier is resistor R5.
The voltage divider R3, R4 and resistor R6 are temperature stabilization elements. The presence of a divider R3, R4 makes the voltage at the base of transistor T1 little dependent on temperature. Resistor R6 in the emitter circuit creates negative DC feedback.
As the temperature rises, the current in the emitter circuit increases and the voltage drop across resistor R6 increases. As a result, the voltage between the base and emitter becomes less negative, which prevents the emitter current from increasing further. The second amplification stage is also assembled according to a common emitter circuit using an MP39B transistor (T2).
To reduce the dependence of the parameters of this cascade on temperature, it uses a combined negative feedback determined by resistors R8, R9 and R10. The voltage amplified by the first stage is supplied to the input of the second stage through the isolation capacitor C2. The load of transistor T2 is resistor R7.
The third amplification stage is assembled on transistor T3. The cascade load is resistor RI8. The connection between the second and third stages is carried out using capacitor C3.
The output stage of the amplifier operates in class B mode in a series-parallel circuit. The main advantage of amplifiers of this class over amplifiers operating in class A is their high efficiency.
When designing conventional low-frequency amplifiers, radio amateurs are faced with the task of manufacturing transition and output transformers. Small-sized transformers with a permalloy core are quite difficult to manufacture. In addition, transformers reduce overall efficiency and in many cases are a source of non-linear distortion.
IN lately output stages were developed without transformers - with quasi-complementary symmetry, i.e. using transistors that have different types of transitions and complement each other to excite a push-pull amplifier.
The transformerless cascade is assembled on two powerful transistors T6, T7 with excitation from a pair of complementary symmetrical transistors T4 and T5 operating in the pre-final amplification stage. Depending on the polarity of the signal supplied from the collector of transistor T3, either one (T4) or the other (T5) transistor is unlocked. At the same time, the associated transistors T6, T7 open. If on the collector of transistor T3 amplified signal has a negative polarity, transistors T4, T6 open, if the signal has a positive polarity, transistors T5 and T7 open.
The direct component of the collector current passing through the thermal stabilizing diode D1 and resistor R19 creates a bias at the bases of transistors T4, T5, which perform the functions of phase inverters. This bias eliminates the characteristic distortions caused by the nonlinearity of the input characteristics at low base currents.
Resistors R22, R23 reduce the influence of the spread of parameters of transistors T4, T3 on the operating mode of the output stage. Separation capacitor C9.
In order to reduce nonlinear distortions, the amplification stages on transistors T3 - T7 are covered by negative AC feedback, the voltage of which is removed from the output of the final amplifier and through the chain R17, C8, R16, R15, C6, R14 is supplied to the base of transistor T3. In this case, variable resistor R17 provides tone control in the area lower frequencies, and potentiometer R15 - in the region of higher frequencies.
If tone control is not required, then parts R14 - R17. C6, C8 are excluded from the scheme. The feedback circuit in this case is formed by resistor R0 (in Fig. 1 this circuit is shown with a dotted line).
For normal operation of the output stage, the voltage at point “a” (quiescent voltage) must be equal to half the voltage of the power source. This is achieved by appropriate selection of the resistance of resistor RI8. Quiescent voltage stabilization is provided by a negative DC feedback circuit.
As can be seen from the diagram, point “a” at the output of the amplifier is connected to the base circuit of the transistor TZ using resistor R12. The presence of this connection automatically maintains the voltage at point “a” equal to half the voltage of the power source (in this case equal to ba).
For normal operation of the amplifier, it is also necessary that transistors T4, T5 and T6, T7 have the lowest possible reverse current. The value of the gain (5 transistors T4-T7 should be in the range 40 - 60; moreover, transistors can have different gain factors h. It is only necessary that the equality h4 * hb = h5 * h7 be satisfied.
Parts and installation
The amplifier is mounted on a getinax panel with a thickness of 1 - 1.5 mm. The dimensions of the board largely depend on the application of the amplifier. To ensure good heat dissipation, P213B transistors are equipped with radiators with a total cooling surface of at least 100 cm2.
The amplifier can be powered from a 12 V battery assembled from Saturn-type cells, or from batteries for a flashlight. The amplifier is powered from the AC mains using a rectifier assembled in a bridge circuit using four diodes D1-D4 with a capacitive filter through a voltage stabilizer (Fig. 2).
As mentioned above, when the amplifier is operating, the current it consumes varies over a fairly wide range. Sudden fluctuations in current will inevitably cause a change in the supply voltage, which can lead to unwanted connections in the amplifier and signal distortion. To prevent such phenomena, stabilization of the rectified voltage is provided.
The stabilizer consists of transistors T7, T2 and a zener diode D5. This stabilizer provides a stable voltage of 12 V when the load current changes from 5 to 400 mA, and the ripple amplitude does not exceed 5 mV. Stabilization of the supply voltage occurs due to the voltage drop across transistor T2.
This difference depends on the bias at the base of transistor T2, which, in turn, depends on the value of the reference voltage across resistor R2 and the voltage across the load (Rload).
Transistor T2 is mounted on a radiator. The rectifier is placed in a box measuring 60X90X130 mm, which is made of sheet steel 1 mm thick.
The power transformer is made on an Ш12 core, the thickness of the set is 25 mm. Winding I (at 127 V) contains 2650 turns of PEL 0.15 wire, winding II (at 220 V) - 2190 turns PEL 0.12, winding III - 420 turns PEL 0.55.
Setup
An amplifier assembled from proven parts and transistors usually starts working immediately. By connecting the power source (12 V), resistors R3, R8, R12, R18 set the recommended mode. Then, through the separating capacitor C3, which is first disconnected from the collector of transistor T2, the voltage from the sound generator (0.2 V, frequency 1000 Hz) is supplied to the amplifier input.
The feedback chain at point “b” must be broken. The output voltage waveform is monitored using an oscilloscope connected in parallel with the loudspeaker. If large “steps” are observed at the junctions of half-waves, you need to clarify the value of resistor R19.
It is selected based on minimal distortion, which almost completely disappears when the feedback circuit is turned on. The setup of other cascades is no different. In cases where a sensitivity of about 250 mV is required from the amplifier, the first two stages on transistors T1, T2 can be excluded from the circuit.
Low frequency. Germanium alloy transistors-n- r MP39B, MP40A, MP41A are used to work in low-frequency amplification circuits and are produced in a metal case (Fig. 56, a - c) with glass insulators and flexible leads, weighing 2.5 g, with an operating temperature range from - 60 to +70 ° WITH. Electrical parameters are given in table. 109.
Silicon pnp transistors MP 114, MP 115, MP116 are produced in a metal case with glass insulators and flexible leads (Fig. 57), weighing 1.7 g, with an operating temperature range from - 55 to + 100 ° C. Electrical parameters are given in table. 110.
Rice. 56. Pinout and overall dimensions of transistors MP39V, MP40A, MP41A (a) and their input (6) and output (c) characteristics in a circuit with common base
Rice. 57. Pinout and overall dimensions of transistors MP114 - MP116
Table 109
Reverse collector current, µA, at U K b = - 5 V and temperature, °C:
20 ............... 15
70 ............... 300
Reverse emitter current, µA, at U EB = - 5 V 30
Maximum constant collector current, mA 20
Collector capacitance, pF, at U K6 =5 In and
f=500 kHz.............. 60
The highest pulse collector current,
mA, at I ESR<40 мА......... 150
Output conductivity, µS, at I e = 1 mA,
U„ b =5 V and f=1 kHz.......... 3.3
Base resistance, Ohm, at I e = 1 mA,
U kb =5 V and f=500 kHz......... 220
Power dissipated by the collector, mW, at temperature, °C:
55 ............... 150
70................ 75
Negative voltage U e v, V.... 5
Table 110
Reverse collector current, mA, at Uc = - 30 V and temperature 20 and 100 °C, respectively... 10 and 400
Reverse emitter current, μA, at U eb = - 10 V and temperature 20 and 100 °C, respectively. . . - 10 and 200
Input resistance, Ohm, in a circuit with OB at LU= - 50 V, I e = 1 mA, f = 1 kHz...... 300
Power dissipated by the collector, mW, at 70°C.................... 150
Mid-frequency. Transistors pnp KT203 (A, B, C) are used to amplify and generate oscillations in the range up to 5 MHz, for operation in switching and stabilization circuits and are produced in a metal case with flexible leads (Fig. 58), weighing 0.5 g, with an operating range temperatures from - 60 to +125°C. The electrical parameters of the transistors are given in table. 111.
Rice. 58. Pinout and overall dimensions of transistors KT203A - B
Table 111
Reverse collector current, µA, at the highest reverse voltage and temperature of 25 and 125 °C, respectively ............... 1 and 15
Reverse emitter current, µA, at U e 6 = - 30 V. 10
Capacitance of the collector junction, pF, at U K b = 5 V and f = 10 MHz ................. 10
Collector current, mA: constant.............. 10
pulse............... . 50.
Average value of emitter current in pulse mode, mA................................. 10
Power dissipated by the collector, MW, at temperatures up to 70 °C......... V. . 150
* For transistors KT203A - K.T203V voltage u k q respectively equal to 50, 30 at 15 V,
High frequency. pnp conversion transistors GT321
(A - E) are produced in a metal case with flexible leads (Fig. 59, a), weighing 2 g, with an operating temperature range from - 55 to +60 ° C. The electrical parameters of the transistors are given in table. 112.
In UT magazines No. 9 and No. 10 for 1970, we talked about simple detector receivers. Such receivers allow you to hear signals from powerful and nearby radio stations in your headphones.
Today you will get acquainted with the simplest transistor amplifier, and also learn what needs to be done to make the receiver even better and how to “teach” it to receive more programs with increased volume.
So, LESSON 3.
WHAT A TRANSISTOR CAN DO
First of all, we need a transistor. This small electronic device, little more than a pea in size, performs the same role as an amplifier tube. The “heart” of the transistor is a miniature plate made of a semiconductor (germanium or silicon) with two electrodes fused into it. One of the electrodes is called the emitter, the other is called the collector, and the plate is called the base (Fig. 1).
If a weak electrical signal is applied to the base of the transistor, then a powerful “copy” of it will appear in the collector circuit. It turns out that the semiconductor triode works as an amplifier. The ratio, which shows how many times the change in the collector current is greater than the change in current in the base circuit that caused it, is called the current gain of the transistor and is denoted by the letter P (beta). You already guessed that the larger the coefficient |3, the greater the gain the triode has.
d For a low-frequency amplifier, low-power transistors such as MP39-MP42 or similar triodes P13-P16 with any letter index are suitable. It is important that their odds
The current gain factor was at least 30-40.
In addition to the transistor T, the amplifier circuit (Fig. 2) includes a resistor R, a capacitor C and an electromagnetic telephone Tlf.
Resistor R is connected between the base of the transistor and the minus of the battery. It supplies voltage to the base and creates the necessary operating mode of the triode. Its resistance is 200-300 kohms and depends on the parameters of the transistor.
Capacitor C is called separating capacitor. It allows audio signals to pass through, but blocks the path of direct current between the base and the positive terminal of the battery.
The fixed resistor R can be of any type. However, it is better to include small-sized devices such as ULM or MLT 0.125 in transistor circuits. Capacitor With a capacity of 0.047 uF type K Yu-7 or MBM, and an electromagnetic telephone (earphone) TLF type TON-1 or TON-2 with a high-impedance voice coil.
Assemble the amplifier circuit on a circuit board made of cardboard or plywood measuring 50X30 mm (Fig. 3).
Transistors are very sensitive to high temperatures
temperature You need to solder quickly and confidently so as not to overheat the triode. The device leads should not be bent closer than 10 mm from the body, and their length should be at least 15 mm.
Setting up the amplifier comes down to checking the operating mode of the transistor. Selecting the value of the resistor R, set the collector current Ti equal to 0.8 - 1 mA. The measuring device must be connected between the headphone output and the battery negative. If you do not have a milliammeter or tester, then you can set the desired triode mode based on maximum volume and good sound quality on the phone.
So, you have assembled a transistor low-frequency amplifier. Connect a microphone to its input terminals
