BD139 Transistor Amplifier Make Easily

About: Share diy projects to those who have the same hobby with me

Hii friend,

Today I am going to make a Transistor Amplifier using BD139 Transistor.This transistor amplifier is working properly.It's output sound depend upon the speaker and source.

Let's get started,

Step 1: Take All Components As Shown in the List/pictures

Components Required -

1.Battery - 9V

2.Battery connector wire


4.Transistor - BD139

5.Resistor - 1K

6.Capacitor - 16V 100uf

7.AUX Cable

Step 2: Connect All Components As Shown in the Circuit Diagram

All components are compulsory for this amplifier.

Step 3: Connect Resistor

Connect 1K resistor to the Collector and Base of the transistor as shown in the picture.

Step 4: Connect Capacitor

Now Connect the +ve of 16V 100uf Capacitor to the base of the transistor as you can see in the picture.

Step 5: Connect AUX Cable

Solder +ve of aux cable to the -ve of capacitor.

and solder the -ve of aux cable to the emmiter of the transistor.

Step 6: Solder Speaker Wire

Now solder the +ve wire of speaker to the emmiter of the transistor.

Step 7: Connect Battery Wire

Next Solder the -ve wire of battery to the -ve wire of speaker.

and the +ve wire of Battery to the collector of the transistor.

Step 8: Connect Battery

Connect battery to the circuit.

Now our BD139 transistor amplifier is ready to play.

Connect aux cable to your phone/laptop/tab/......etc and play songs and enjoy

Step 9: Enjoy With Full Volume

Hii friend,

I made everyday new projects in this blog.If you like your blog then visit everyday to make new projects.

Thank you



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    7 Discussions


    15 days ago on Step 9

    This circuit IS NOT designed correctly. First, the base MUST have a series resistor for proper operation. Second, the audio signal is shown as entering the negative side of a coupling capacitor. This IS NOT correct.


    2 replies

    Reply 15 days ago

    You are write but amplifier is working 100% in this circuit diagram.
    thanks for comment