The design is pretty simple and easy to build. The main delay effects IC is PT2399 which is a cheap solution compared to using complicated and more expensive BBD IC such as MN3207 and the like. PT2399 is digital echo processing IC capable of producing up to 342mS delay with 1.0% THD. You can further expand this to more than 1 second but with the price of higher harmonic distortion which gives not pleasant sound. The resolution of the ADC of the IC is not disclosed on its datasheet, but it sounded good so I guess it’s around 16bit maybe.
The biggest problem in PA system that most technician hate most is the mic feedback. Feedback is not that hard to eliminate as long as you know what is the cause. There are several common sources of feedback that I will share to you and simple solutions to kill feedback on your system.
Here’s a simple tone control design for your home audio system to boost your BASS and treble for more live sound. The circuit is composed of a transistor amplifier to boost the signal because it will be attenuated by the RC filter circuit.
Building a “hum-free” audio is not easy till you know what you are doing. It is not as easy as connecting wire into where it should be connected. Especially for grounds, if you connected it into wrong point. Noise usually come from ground loops or connecting a very sensitive signal ground line to a high current ground path. In most cases a star connection is very effective in eliminating the noise.
There are lots of bluetooth speaker on the market today. But if you have an old mini component or a sound system that is still working and sounds good, why won’t you just upgrade it and put a bluetooth functionality? There are lots of audio bluetooth receiver on the market today.
One of my project: a led watch with 71 SMD LED. The microcontroller is a Microchips PIC16F728 running in 4MHz crystal oscillator and powered by CR2032 battery.