I just noticed that many of my visitors are searching for DIY DI Box so I decided to make another design project for DI Box. This will be powered by a 9-15V AC/DC adapter or a 9V battery.
About the Circuit
The circuit is basically made up of 2 opamps, 1 is configured as a buffer and the other one is configured as an inverting opamp.
R2 and R3 is used as a voltage divider to provide 1/2VCC for the opamp. This is needed for single supply operation of opamp. At single supply, the output of the opamp cannot swing at negative voltage so the output of the opamp is offset to 1/2VCC so the output can swing below 1/2VCC for negative voltage and above 1/2VCC for positive voltage swing. at the output stage, a capacitor is used to remove the DC offset and output only the AC voltage. C5 is used to filter the 1/2VCC from the voltage divider R2 and R3. R1 and C1 is used to filter the supply. This is used to filter out the 60Hz/120Hz line noise on the supply. If you are using a battery, you can just remove R1 instead. Potentiometer value can be 100k to 1M. I used RCA connector simply because I can’t find any Audio phone jack on my library and I don’t have time to search for it.haha
C6 and C7 voltage rating should be at least 50V, this is to protect the cap when phantom power is accidentally turned on. Other capacitors can be rated 16V and above.
Phantom Powered DI Box
If you want it to be powered via Phantom power of mixer, you can check this version of my DI Box here: https://tataylino.com/diy-di-box/
You just need a 1/2W 6.8k resistor and a 15-30V zener.
PCB Design
PCB design is made with KiCad, a free open source software. Designed with 1 layer PCB for easy DIY at home.
3D Render
