A DI box or Direct Injection box is a very useful piece of equipment used to connect keyboard, guitars and other audio signal source directly to the mixer. DI box function is to convert the unbalanced output of the guitar, keyboards and other musical instrument to balanced output. Connecting an unbalanced output to balanced input of the mixer often led to humming noise which is really unpleasant for ears especially when no one is playing the instrument.
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.
DMX or DMX512 is short for Digital MultipleX(the number 512 represents the max number of channels), a communication protocol mainly made for lighting controls. It was introduced in 1990’s and was developed by Engineering Commission of United States Institute for Theatre Technology (USITT). On that time, DMX512 is so expensive to design and implement. Only today with the advancement of technology, anyone can now develop their own DMX512 device.
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.
With the use of microcontrollers, designing a DMX512 controlled led lights is now easier. DMX512 stands for Digital Multiplex which was developed by Engineering Commission of United States Institute for Theatre Technology (USITT) way back in 1990’s. Way back in 90’s era, it takes hardwork to design a DMX controlled lights.
In the first lesson, we learned the keys of the piano. On this lesson we will now learn the basic chords on a piano. There are 12 basic chords(also known as “triads” because it is composed of 3 notes) in a piano. Chords in piano are the same as in guitar. All chords of guitar has its own corresponding chords in piano. So if you already know how to play guitar then it will be easier for you to understand and learn this lesson. Below are the basic Majorchords of a piano. Don’t be confused with the chords with “/”, for example A#/Bb means that A# and Bb are just the same. You can use A# in replacement to Bb and vice versa.