Engineering and Construction
Pages 14 (3514 words)
Roberto del Rosario described Karaoke Sing-Along System (Patent No. UM-5269 dated 2 June 1983, Patent No. UM-6237 dated 14 November 1986), which he invented in 1975, as a handy multi-purpose compact machine that incorporates an amplifier speaker…
With Karaoke's continually growing popularity over the years‒in all aspects of the community worldwide (i.e. home entertainment, business, etc.), the researchers came up with their sort of own version of Karaoke as a transistor application.
The project, entitled "Transistor Level Implementation of Karaoke Machine with six-band Graphic Equalizer," aims to develop a transistor-based, Karaoke-type amplifier that is able to run from the mains power supply and consists of the following elements:
1. a 12-V regulated power supply,
2. two inputs: a microphone and a line input,
3. a Common-emitter mixer/preamplifier stage,
4. a six-band graphic equalizer stage,
5. a Common-emitter voltage amplifier stage,
6. a Common-collector power amplifier stage, and,
7. a loudspeaker output;
as indicated in the schematic diagram below.
Circuit Design and Operation
Power supplies, as defined by Howard (1998), are electronic circuits, basically composed of four sections: transformer, rectifier, filter, and regulator, designed such that an input ac signal is converted to dc, at any desired level. Shown below is a block diagram of a basic power supply.