BD138 Transistor Pinout, Equivalent, Features, Applications

BD138 is a TO-126 packaged PNP BJT transistor, below you will find BD138 transistor pinout, equivalent, features, applications, datasheet and other useful information about this device.


BD138 Transistor Pinout, Equivalent, Features, Applications


Features / technical specifications:

  • Package Type: TO-126
  • Transistor Type: PNP
  • Max Collector Current(IC): -1.5A
  • Max Collector-Emitter Voltage (VCE): -60V
  • Max Collector-Base Voltage (VCB): -60V
  • Max Emitter-Base Voltage (VEBO): -5V
  • Max Collector Dissipation (Pc): 12.5 Watt
  • Max Transition Frequency (fT): 190 MHz
  • Minimum & Maximum DC Current Gain (hFE): 25 – 250
  • Max Storage & Operating temperature Should Be: -55 to +150 Centigrade


NPN Complementary:

NPN Complementary of BD138 is BD137


Replacement and Equivalent:

BD140, BD238G, MJE171, MJE702, BD792, BD168, BD180, BD190, BD236, MJE235, MHE253, 2SB1354, 2SB1355, BD378-16


BD138 Transistor Explained / Description:

BD138 is another PNP transistor of BD13x series of PNP and NPN transistors which also contains other PNP transistors like BD136 and BD140. BD138 transistor can be used for any general purpose switching and amplification purposes. The max collector current of the transistor is -1.5A that is quite acceptable to use this transistor to drive variety of loads in a circuit with the maximum load operating voltage of 60V DC. As mentioned above this transistor can also be used as an amplifier and it can provide the max output power of 12.5W.


Where We Can Use it & How to Use:

BD138 can be used for any general purpose switching and amplification purposes, when using as a switch it can handle max load of -1500mA that is enough amount of current if you want to drive common loads in your circuits that falls under 1.5A. The loads can be high power LEDs, relays, solid state switches, high power transistors, DC motors etc.

On the other hand it can be used to amplify audio and other kind of electronic signals it can also be used in audio amplifier stages or it can be used as a separate amplifier at the output of audio circuits to drive a speaker. BD138 is a BJT transistor and it can be used / wired as you wire a normal BJT transistors it can also be replaced with a TO-92 transistor if you want a little bit higher load or amplify a signal more as compare to a TO-92 BJT transistor.



Audio Amplifier Stages
Output of an Audio Device to Drive a Speaker
Switching Loads under 1.5A
Battery Charger Circuits
Power Supply Circuits
Motor Driver Circuits
Darlington Pair Circuits


How to Safely Long Run in a Circuit:

To get long term performance from BD138 it is recommended to use a proper heatsink with the transistor, do not drive load of -1.5A and 60V though this transistor, it is always better to stay some values below from the maximum ratings to save the transistor from stress. Do not store or operate the transistor below -65 Celsius and above +150 Celsius.



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