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Tag: BD139

  • BD139 Pinout

    The BD139 is a general-purpose NPN bipolar junction transistor (BJT). It has three pins: There are two companies that manufacture the transistor The pinout diagram according to STMicroelectronics is as follows: When looking at the center hole and keeping the metal side down the pins are arranged from right to left as: It’s important to…

  • FAKE BD139 NPN transistors

    I have recently found out that there are FAKE transistors in the market. I have a built a circuit design and when I bought the transistor from the Lajpat rai market in Delhi; I assembled the circuit on a test bench for measurements. But I was surprised that the BD139 did not work with 10mA…