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How does a 2N3055 transistor work
/ 2018/6/20 12:04:49 / News

What is a 2N3055 transistor

2N3055 transistor is a NPN power triode. Main data: 15A, 50V, 115W. 2N3055's complementary symmetric PNP tube or its replacement is: MJ2955.

This 2n3055 was introduced by RCA using a hometasial power transistor process when in 1960s. According to JEDE standard,it’s a transistor type of enduring popularity.

2N3055 transistor image

2N3055 main attributes




Separate semiconductor products


Transistor(BJT)-single path

Type of transistor:


Current collector(Ic) (maximum):


Voltage Colector Emitter Breakdown(max):


Vce saturation (maximum) under Ib and Ic conditions:

3V @ 3.3A, 10A

Current collector cut-off (maximum):

700 mu A

The minimum DC current gain (hFE):

20 @ 4A, 4V at a Ic and Vce.

Power - maximum:


Frequency conversion:


Installation type:

base installation

Package / shell:

TO-204, TO-3

2N3055 Application

The 2N3055 triode has three electrodes, a base pole (B), a collector (C) and a emitter (E). The triode is a current type control device. The current of the base to the emitter controls the current of the collector to the emitter, and the triode has three states, cut-off, amplification and saturation, and two PN knots inside the 2N3055 three pole, and the emitter junction (PN junction between the base and emitter). The collector junction (the PN junction between the collector and the emitter) is the cut-off of the emitter junction, the collector has no current on the collector, and the collector junction conduces to the complete conduction between the collector, and the current of the collector varies with the current of the emitter (the transistor can amplify the current, and the current on the collector is equal to the current of the emitter multiplier by the magnification. " The saturation is that the emission junction is fully conductive and the collector current is the largest. According to the polarity of PN, they can be divided into two kinds of triode, NPN and PNP. Their functions and functions are the same, but the direction of current is different. Transistors are usually used as signals to amplify or switch devices in circuits.

2N3055 pin

2N3055 pinout

The 2N3055 triode has three electrodes, a base pole (B), a collector (C) and a emitter (E). In the above picture, 1=B, 2=E, TAB=C .

How to test 2n3055 transistor

1. In general,after we assure their pins, insert the transistor into your breadboard. If the leads on the transistor are too large for your breadboard contacts, you will need to attach wires to the leads and insert the wires into the breadboards. Ensure that the three transistor terminals are not connected to the same contact strip (the contact strips usually run vertically). This would short out the transistor.

2. Insert a 1 k-ohm resistor into the breadboard. Arrange it so one lead is connected to the base of the transistor.

3. Insert a 100 ohm resistor into the breadboard. Arrange it so one lead is connected to the collector of the transistor.

4. Connect one positive supply voltage to the unconnected lead of the base resistor, and connect the other positive supply voltage to the unconnected lead of the collector resistor. These connections can be made with wires or with clip cables that plug into the power supply.

How to test 2n3055 transistor

5. Connect the negative terminals of the supply voltages to one of the long "bus" strips on the breadboard (these usually run horizontally at the top and bottom of the breadboard). This provides a "ground rail."

6. Insert a wire that connects the emitter of the transistor to the ground rail.

7. Turn on the power supply. Set the collector voltage supply to 10 Volts and the base supply to 0 Volts.

8. Touch the probes of the voltmeter to the leads of the collector resistor. The voltage should be zero volts, because with no base voltage, the transistor is turned off, so no current is passing through the resistor.

9. Gradually increase the voltage supply that is connected to the base resistor, and watch the reading on the voltmeter. The base-emitter voltage of the 2N3055 is about 1.8 Volts. As the voltage supply approaches 1.8 Volts, the transistor should start to turn on. As this happens, current is driven through the collector resistor, so a voltage should appear across this resistor. This voltage should increase as you continue to increase the supply past 1.8 Volts.

How does 2N3055 work

Now, I will use several 2n3055 circuit to explain how does 2n3055 work.

  • 2n3055 linear regulated power supply circuit diagram

2n3055 linear regulated power supply circuit diagram

The following diagram is a circuit diagram of a linear regulated power supply consisting of a power triode. 2N3055 can be replaced by other triode of the same specification. 2N3417 can be used in BD139 or other triode, diode 1N914 can also use the common diode 1N4148. T1 to convert 6V to 7V transformer with 220V (or 110V). If the transformer with 1-2A output current, output current of the measuring circuit is about 1A.


  • step down dc dc converter circuit diagram basic on 2n3055 transistor

Inductance buck DC/DC converter: the circuit schematic diagram is shown in the diagram.

step down dc dc converter circuit diagram basic on 2n3055 transistor

In the picture, VIN is the input voltage, the VOUT is the output voltage, the L is the energy storage inductor, the VD is the continuous current diode, the C is the filter capacitor, the R1 and R2 are the voltage divider, and the error feedback signal FB is produced after the partial pressure, which is used to stabilize the output voltage and the output voltage of the output voltage. The power switch tube V can use N channel insulated gate field effect tube (MOSFET), and also use P channel field effect tube, of course, it can also use NPN transistor or PNP type transistor. In practical application, the majority of P channel field effect tubes are generally used.

The basic principle of Buck DC/DC converter is that the V switch tube operates in the switch state under the control of the control circuit. When the switch tube is connected, the FIN voltage is made up of the switch tube S, D pole, energy storage inductor L and capacitance C. The charging current not only establishes the DC voltage at both ends of the C, but also produces the left positive and right negative electromotive force on the energy storage inductor L. During the switch tube cut-off time, because the electric current in the energy storage inductance L can not be mutated, the L is produced by self inductance. The right positive and the left pulse voltage. As a result, the L right positive voltage - the filter capacitor C a continuous current diode VD - L left end constitutes the discharge circuit, the discharge current continues to establish the DC voltage at both ends of the C, and the DC voltage at both ends of the C is supplied to the load. Therefore, the output voltage of the buck DC/DC converter is not only small, but also the peak voltage of the switch tube is low.

  • 2n3055 audio amplifier circuit diagram

The audio power amplifier has simple circuit and low cost. The best power supply voltage is about 50V, but this circuit works from 30 to 60V. The maximum audio input voltage is about 0.8 - 1V, and the output power is about 60W. The last transistor 2N3055 can be any NPN type power transistor, but don't use Darlington type.

2n3055 audio amplifier circuit diagram

The C1 regulates low frequency (bass), and as the capacitance increases, the low frequency becomes louder and louder.

The C2 regulates a higher frequency (Gao Yin), and as the capacitance increases, it becomes louder and louder at higher frequencies.

This is a class B amplifier, which means that the push-pull output transistor must be applied to a quiescent current, even without any input signal. The current can be regulated by a 500 Omega resistor setting.

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