Dilshan R Jayakody’s Web Log

The QN8035 is a stereo FM radio receiver launched by the Quintic Corporation . Compared to other popular digital FM tuners ( RDA5807 , TEA5767 , etc.), this tuner does not seem to be as popular among the DIY community. As we have seen, the biggest problem with this IC is the lack of information. During our initial search, we came across some details about this IC. Much of that information was confined to a product datasheet and a few undocumented GIT repositories. Based on the information we found on the internet, we concluded that Quintic was no longer in business. According to the NXP website , it stated that Quintic Corporation was acquired by NXP in 2015.  Although the Quintic is no longer in business, the QN8035 IC can still be purchase at a low price from online stores. In addition, we found several FM radio kits manufactured using this IC in online stores. Due to the lack of information, I decided to explore this IC to understand its functionality and limitations. In t...

This project is about 24-bit stereo DAC, which we build for Raspberry Pi boards. This R-2R ladder DAC is developing around Intel / Altera EPM240T100C5N CPLD. We developed this module after review the PT8211 DAC, which we tested a few months ago. Compare with PT8211 DAC, this module is capable to provide high-quality audio output with Raspbian OS . A finished prototype of the R-2R DAC. At the testing stages, we drive this DAC with the I 2 S bus of the Raspberry Pi 3 Model B board . The provided device tree overlay is developed and tested on the new Raspbian Buster OS. The audio quality of this DAC is impressive. In most of the circumstances, we test this unit using mpg123 player and got excellent results. The MCP602 opamp of this module is capable to drive a headphone, and for the testing, we use Audio Technica ATH-PRO500MK2BK headphones directly with this module. Also, we pair this module with several AF power amplifiers and obtained superior results. The most n...

In this project, we build a simple I 2 S stereo decoder with an amplifier. To decode I 2 S data we use Princeton Technologies PT8211 16bit DAC. KA2206 audio power amplifier is used as the driver stage of this system. The prototype version of I2S stereo decoder Structure of this I 2 S amplifier is self-explanatory from the schematic. We select PT8211 and KA2206 combination due to lower cost and availability. Unfortunately, PT8211 DIP package is not available in the local market and we use SO package in our prototype. We design PCB for the DIP packages, and therefore we solder PT8211 SO package to PCB using " SO8 to DIP8 " converter. We design this system to work with 9V DC power source but at the prototyping stages, we noticed that it works well with lower DC voltage such as 5V. For the output use any 8Ω or 4Ω (5W or higher rated) full range speaker pair. We test this with 8Ω 8W oval speakers which are commonly found on televisions.

WebRTC is a web technology to enable peer to peer communication in real-time. It mainly uses to create video conferencing and chat applications using web browsers. In this post, we describe how to enable this technology in QtWebEngine on Raspberry Pi 3 platform. QtWebEngine is an embedded browser component which comes with the Qt framework . This component is based on Google Chromium browser and it supports most of the Chromium features including WebRTC. In PC, WebRTC applications run smoothly on QtWebEngine component. But in Raspberry Pi platform situation is different and none of the WebRTC application is work with the QtWebEngine. The only thing which we can see is a black box in an HTML5 video tag area. At the time of writing this problem exists in Qt version 5.6, 5.7 and 5.8.