2N4125 Transistor Pinout, Equivalent, Uses, Features, and Other Information

If you are looking for a general purpose transistor that can be used in your applications for general and small signal requirements then 2N4125 can be a good choice. The transistor is almost identical to the popular 2N3906 and other similar transistors like it. The post below contains 2N4125 transistor pinout, equivalent, uses, features, and other information such as where and how to use it and safe operating guidelines.


2N4125 Transistor Pinout, Equivalent, Uses, Features



Features / Technical Specifications:

  • Package Type: TO-92
  • Transistor Type: PNP
  • Max Collector Current(IC): -200mA
  • Max Collector-Emitter Voltage (VCE): -30V
  • Max Collector-Base Voltage (VCB): –30V
  • Max Emitter-Base Voltage (VBE): –4V
  • Max Collector Dissipation (Pc): 625 mW
  • Max Transition Frequency (fT): 200 MHz
  • Minimum & Maximum DC Current Gain (hFE): 25 to 150
  • Max Storage, Operating & Junction temperature range: -55 to +150 Centigrade


Replacement and Equivalent:

2N4126, 2SB1288, 2SB1212, 2SB1059, 2SB1041, 2SA1625, 2SA1056, 2SA1054


2N4125 Transistor Explained / Description:

2N4125 is a PNP small signal bipolar junction transistor. It is a general purpose transistor available in TO-92 package. A general purpose transistor means it can be used for any type of general switching and amplification purpose that falls under its ratings so if it is used as a switch it can drive load of upto 200mA and as an amplifier it can be used upto 200MHz.

As already mentioned this transistor is almost identical to the popular 2N3906 so you can use it in any application in place of 2N3906.

When looking at the specification of the transistor we can see that the max collector to emitter voltage is 30V, max collector current (Continuous) is 200mA, DC current gain is 25 to 150, max power dissipation is 625mW, max transition frequency is 200MHz, max noise figure is 5.0dB and collector to emitter saturation voltage is 0.4V.


Where We Can Use it & How to Use:

As mentioned it is a general purpose small signal transistor so it can be used in wide variety of applications such as driving small motors, relays, LEDs, ICs, microcontrollers, high power transistors etc. Moreover it can also be used for variety of small amplification purposes and also in radio and RF circuits under 200MHz.



Audio amplifiers

Switching loads under -200mA

RF Circuits

Signal amplification


Safe Operating Guidelines / Absolute Maximum Ratings:

Following are the safe operating guidelines of the transistor.

  • Do not use the transistor to its absolute maximum ratings and always stay 20% below from its absolute max ratings. Using a transistor on its absolute maximum ratings is not recommended by the manufacturer and it may damage the transistor or weak its performance.
  • Maximum continuous collector current of the transistor is -200mA therefore do not drive load of more than 160mA.
  • Max collector to emitter voltage is -30V therefore do not drive load above -24V.
  • Always store or operate the transistor above -55°C and below +150 °C.



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