In case you want to connect your audio mixer or electronic piano or any other line level audio equipments to your computer or laptop for recording, here is a simple USB audio interface circuit that does the job. It is based of PCM29XX IC from TI. This is used in many analog audio mixers with usb interface such as the Behringer Xenyx USB mixer series.
About USB audio interface circuit
This circuit is USB powered. The IC has 16bit delta sigma ADC and DAC and capable of up to 48kHz sampling rate. it has stereo line level input and outputs.The crystal needed is 12MHz.
Quick PCB design
Here is a simple PCB layout that I designed using kicad software.
Want to have a copy of the Kicad design? Just like my facebook page and send me a message. thanks for visiting… 🙂
Since I needed this circuit for my recording may piano and guitar covers, I built my own using universal PCB. This is what I used on my guitar and piano covers on my youtube channel here.
There’s no need for drivers, it installs automatically when you plug it in. It has 16bit ADC/DAC with up to 48kHz sampling which is good enough for recording. 16bit/48kHz might not sound great but it is actually good. This chip is used by Behringer on some of their Xenyx USB mixer and also on their cheap usb audio interface. The audio quality is not the best but it is better than those cheap USB sound card on the market. This is good enough for recording for you youtube content.
Here is the actual video of my prototype in action.
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USB audio interface Parts list
|C1||1u||16V electrolytic capacitor|
|C3||4.7u||16V electrolytic capacitor|
|C4||4.7u||16V electrolytic capacitor|
|C5||1u||16V electrolytic capacitor|
|C6||1u||16V electrolytic capacitor|
|C7||1u||16V electrolytic capacitor|
|C8||1u||16V electrolytic capacitor|
|C9||1u||16V electrolytic capacitor|
|C10||1u||16V electrolytic capacitor|
|C11||4.7u||16V electrolytic capacitor|
|C12||4.7u||16V electrolytic capacitor|
|J2||Input||3pin JST connector|
|J3||output||3pin JST connector|
|R1||2.2 ohms||Resistor SMD or 1/4W or 1/8W|
|R2||1M||Resistor SMD or 1/4W or 1/8W|
|R3||1M||Resistor SMD or 1/4W or 1/8W|
|R4||1.5k||Resistor SMD or 1/4W or 1/8W|
|R5||22 ohms||Resistor SMD or 1/4W or 1/8W|
|R6||22 ohms||Resistor SMD or 1/4W or 1/8W|
|R7||1M||Resistor SMD or 1/4W or 1/8W|
|R8||1M||Resistor SMD or 1/4W or 1/8W|
|R9||1M||Resistor SMD or 1/4W or 1/8W|
|R10||220 ohms||Resistor SMD or 1/4W or 1/8W|
|U1||PCM2902C||USB interface IC|
The parts list does not include input and output connectors, you may opt to use RCA or phone jack connector.
I am planning to build an improve version of this device and sell it online so stay tuned! Subscribe to my youtube channel and facebook page to keep you updated! 🙂