D718 amplifier heavy bass controller

In this video i am showing, how to make a single transistor low efficiency D718 amplifier with heavy bass controller. I used here a 50k pot with a pair of 104J capacitors as low pass filter for subtracting the high frequency. I am using here 12v/5 amps PC power supply. You can increase the voltage upto 18v for more output. Also using a 4 ohms speaker and getting good results.

I used here very few components which will help beginners and students to assemble it easily. This is a very low efficient amplifier and provided for educational purpose. I don’t recommend it for professional use.

Circuit diagram

Following is the circuit diagram of single D718 transistor amplifier. One 0.22 ohms 5 watts load resistor is highly recommended to connect in between collector and the positive supply of 12 volts. Note that this resistor is not shown in circuit diagram and the project video.

D718 Amplifier Heavy Bass Circuit Diagram

Development images

Stick the D718 transistor onto the heat sink and tight it well for heat dissipation. Connect one 680 ohms resister to pin.1 base and pin.2 collector. Place one 4700uf capacitor onto the heat sink or any where and connect its positive end to pin.2 collector of D718 transistor for speaker’s output.

D718 Amplifier Heavy Bass Image1

Connect positive end of 220uf capacitor to pin.1 base of d718 transistor and solder its negative side to the center pin.2 of volume controller for audio input. Also take a piece of black wire for ground and connect its one end to pin.3 emitter of transistor and the other end to left most pin of volume controller.

D718 Amplifier Heavy Bass Image2

Now attach the power supply connections. The red wire +12v will go to pin.2 collector and black ground will go to pin.3 emitter of D718 transistor.

D718 Amplifier Heavy Bass Image3

Attach the ground wire of 3.5mm audio jack to left most pin of volume controller and the left & right channel wires to right most pin of volume controller.

D718 Amplifier Heavy Bass Image4

Now attached the two speaker’s wire. The minus side (yellow) will go to pin.3 emitter of transistor and the plus side (green) will go to the negative pin of 4700uf capacitor. Take two 104 ceramic capacitors, join them in series and solder their both ends to pin.1 & pin.3 of volume controller.

D718 Amplifier Heavy Bass Image5

Insert the 3.5mm audio jack into your mobile phone. Play the music and enjoy the project. I really appreciate and thankful for watching video and visiting this post of my website. Good luck.


List of components

used in D718 amplifier heavy bass

  • D718 transistor NPN x 1
  • 4700uf capacitor x 1
  • 220uf capacitor x 1
  • 680 ohms resistor x 1
  • 50k potentiometer x 1
  • 12 volts dc power supply
  • 4 ohms speaker
  • A large enough heat sink.
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3 comments on D718 amplifier heavy bass controller

  1. the diagrams is wrong: the voice coil must be en serie with the plus power supply otherwise you will destroy both output transistor and poser supply.


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