Low-cost active D.I. box

About me:

Hi, I’m an electrical engineering student at the University of California. Currently, I’m working on projects relating to health monitoring wearable devices. My research area is about developing non-invasive biosensors such as glucose sensor and heart pulse sensor. My hobby is working with audio system.

About this project:

As we all know, when routing a long-distance audio cable using a common guitar jack, which is in the form of Unbalanced, the resulting signal may cause a loss or drop of the signal. D.I. box, or direct injection box, is a device that converts the signal from Unbalanced to Balanced signal so we can wire the audio cable over long distances minimising the loss of signal and preventing interference from unwanted signals to achieve good sound quality. This project is to build a low-cost active D.I. box circuit based on TL072, a low-noise JFET-input op-amp, but achieve a studio quality sound. The power is supplied by 48-volt phantom power from the XLR output that is delivered by the audio mixer.


  1. 1 input channel (TRS)
  2. 1 link (TRS)
  3. 1 output (XLR)
  4. 48v phantom powered/ 9v battery
  5. Studio quality sound
  6. Overvoltage protection
  7. Power filter circuit

### Words to PCBWay ###

I have ordered PCBs from PCBWay for almost all my projects. PCBway provides high-quality PCB manufacturing for an affordable price. Surely, all my future project's PCB will be ordered from PCBWay!

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Oct 08,2020
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