Mp3 speaker with RDA5851s

Today I’ve disassembled MP3 speaker and noticed RDA’s chip inside.Very interesting solution. Speaker itself provided powerfull bass until it burnt out. I will dig deeper later to understand what part caused the problem. This company’s products include RDA3560M satellite downconverter IC which I am interested in. Such products are mainly interesting because they are cheap mass production IC’s. With some effort you can use theirs IC functionality and significantly reduce costs.


New article “Microwave Substrate Dielectric Constant Estimation Using Dielectric Resonator Oscillator”

You can download PDF here. Main idea is to measure wavelength in dielectric without using expensive equipment. Only dielectric resonator is required.


This paper presents a simple method for determining relative dielectric constant of microwave PCB substrates without involving expensive equipment. Microstrip oscillator with elongated feedback arms is etched on a substrate being measured. Dielectric resonator is moved and aligned along feedback arms in different positions. Each position which result in build up of oscillation is marked on PCB surface. Distance between marks is then measured and used to calculate relative dielectric constant.