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In this project, we’ll teach you making a simple 12v amplifier circuit. To make this circuit we are using transistor. If you have DC-12v adapter or 12v battery, then you also can make this amplifier circuit at home easily. And by using a DC-12v transformer you can easily make a powerful power supply for the circuit.

To make this powerful amplifier circuit, we might need some electronics component. First we will introduce with those electronics components.

Component List :

1. Transistor – 2SA 1943

    Transistor – BD 139

2. Heat Sink

3. Screw

4. Volume – B 100K

5. Resistor – 10 KΩ

                     47 KΩ

                    680 Ω

                    0.47 Ω (5 watt)

6. Capacitor - 220µf/ 16v

7. Audio Input Cable

8. Power – DC 12v

9. Sound Speaker

Transistor Pinout –

2SA 1943 – 

It is a PNP transistor. As usual the transistor 2SA 1943 also contain 3 leg & this 3 leg’s also have 3 different names. If we count it’s leg from left side, then 1no “Base”. 2no “Collector” & 3no “Emitter”

BD 139 - 

It is an NPN transistor. As usual the transistor BD 139 also contain 3 leg & this 3 leg’s also have 3 different names. If we count it’s leg from left side, then 1no “Emitter”. 2no “Collector” & 3no “Base”

Circuit Connection -   

To make this amplifier circuit, 1st we connect 2SA 1943 Transistor  “Base” leg with “Collector” leg of BD139 transistor. Then we connect 47 KΩ resistor with “Base” and “Collector” leg of BD139 transistor. We connect 680 Ω resistor with “Emitter” leg of BD139 transistor.

To complete the circuit connection, now we need to connect 10 KΩ resistor. We connect this resistor with “Base” leg of BD139 transistor and other terminal with 680 Ω resistor.

Now we connect 220µf/ 16v capacitor with the circuit. We connect capacitor positive leg with “Base” leg of BD139 transistor. Then we connect 0.47 Ω (5 watt) resistor with the circuit. We connect this resistor with “Collector” leg of 2SA 1943 transistor. We connect volume with the rest terminal of resistor.

Again we connect volume with capacitor negative leg. It is the time to connect audio input cable with the circuit. We connect audio input cable with volume/ potentiometer.

Then we connect power source, with the circuit. For power source, we are using DC-12v. We connect DC 12v positive(+) cable with sound speaker. Then we connect a blank cable with the rest terminal of sound speaker. 

Now we connect the other terminal of blank cable with “Emitter” leg of 2SA 1943 transistor. At last we connect DC 12v negative(-) cable with volume/ potentiometer.

Finally our circuit is now ready for use. Now we just connect audio input cable with sound source. Then play music and enjoy the sound.