D718 amplifier heavy bass controller

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

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 and long time use.

D718 amplifier heavy bass controller
D718 amplifier heavy bass controller

Circuit diagram

of D718 amplifier heavy bass

Following is the circuit diagram of single D718 amplifier heavy bass. 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 resister is not shown in the following circuit diagram and the project video. Two 104 ceramic capacitors are also not shown in the circuit diagram. You attached one ceramic capacitor to pin.1 and pin.2 of 50k potentiometer. And the other ceramic capacitor you attach and solder with pin.2 & pin.3 of 50k potentiometer.

D718 Amplifier Heavy Bass Circuit Diagram

More Circuit Layouts

Development images

used in D718 amplifier heavy bass

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 or any audio source. Play music and enjoy the project. I really appreciate and thankful for watching video and visiting this article of my website. Please share it with your friends. Good luck.

D718 Amplifier Image6

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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12 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.


    1. May be you are using more than 4 ohms speaker. Join two speakers in parallel.
      Or may be your power supply is very low ampere. The sound is very high as you can see in the video.
      Thanks for visiting the site and comments.

    2. This circuit has the transistor hooked directly to the power supply, which is completely wrong. If your using something like a battery, there will be no audio as the transistor will essentially be just passing LOTS of current without any output. In order to have any audio, there must be voltage variation at the collector of the transistor, which there wont be without adding a dropping resistor. Try adding the loudspeaker (and a 5 Ohm resistor if the speaker is small) in SERIES with the collector of the transistor. It will then at least make some form of audio. I also suspect the static is from your power supply as its not happy being shorted out by the transistor.

  2. Im getting a bit confused of the potentiometer value, in the video, it is a 10k pot but in the website, its value changed to 50k, so which one is correct.
    In addition, would you please explain the responsibility of those two ceramic capacitors 103? How it will affect the circuit if we miss them.

  3. No se trata de modificar el circuito como se desee, aunque sea para novatos; la propuesta del circuito debe ser realista, NUNCA se conecta en paralelo el EMISOR-COLECTOR de un transistor con el POSITIVO-NEGATIVO de la fuente de alimentación, es una estupidez. En cualquier momento que se polarize la base, el transistor pasa del estado de corte al de saturación, y la fuente de alimentación quedaría conectada en modo CORTO-CIRCUITO. Para evitar esto se conecta en serie una resistencia limitadora y la bobina del parlante, la resistencia debería limitar la corriente a un 80% de la corriente de colector.

  4. Sir ager yeh video app ki shi nhi hai ager app is power supply mai resistor lagana bhul gaye hai to dubara se video upload ker dete youtube mai khi apne nhi bataya tha 12 v+ mai 0.22 ohm ki resistor add kerni hai mera to transistor power detey hi khrab ho geya plz ise correct kijye ic D718 buhat costly hai

  5. I have 2 d718 transistors
    I have 1 2sc5200 transistor
    Which resistor will be batter to build amplifier to use 12 volt

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