CONVERTING CD ROM DRIVE TO AUDIO CD PLAYER

Here is the simplest scheme for converting a CD ROM drive of your computer to a Audio CD player. The minimum requirement for the player is that, it should have a audio output and skip button.The CD ROM drive needs two voltages, 12V & 5V for its operation. So the main objective is to build a suitable power supply for the CD ROM drive. The IC1 (7812) together with associated components produce a regulated 12V DC. The IC2 (7805) together with associated components produce a regulated 5V DC. These voltages as well as ground can be connected to the corresponding voltage pins of the CD ROM drive using a male type CD ROM drive power connector. The 12V can be connected to the yellow wire of connector, 5V to red wire and GND to black wire as shown in figure1. Now the power supply is ready.

Testing

Make the circuit as shown in the circuit diagram. Power up the circuit after connecting the power connector to the CD ROM drive. Now the power LED of the drive will glow.Insert the audio CD. Now the music will be available at the audio output socket of the drive.It can be heard using a headphone. The skip button of the drive can be used to play next song.

By connecting the audio output to a power amplifier you can enjoy the music in a greater wattage.

Circuit Diagram with Parts list

Notes

• For car stereo applications you don’t need the transformer,rectifier and the 7812 regulator. 12V will be available from battery.You just need to produce a 5V from it using a 7805 based regulator. Connect the corresponding voltages to the connector as shown in figure 1 and connect the connector to drive.Done.
• The amplifier for the car audio CD player must be one operating from 12V.
• Do not connect the voltages to CD ROM drive in wrong polarity.Double check the voltages using a multimeter. Wrong polarity could easily damage the drive.

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CD Rom Drive as Digital Audio CD Player

A CD-ROM drive can be used as a stand-alone unit for playing digital audio CDs without interfacing with a computer. The stereo output of CD player available at the audio jack can be amplified using audio input facility which is normally available on a tape-deck/tape-recorder or a stereo amplifier. Audio socket on front/rear of the CD-ROM drive is capable of driving headphones or speakers of less than 500mW. Proper stereo jacks for interconnection between CD-ROM drive and tape deck are available from computer/tape recorder spares vendors. The principle of operation is illustrated here with the help of block diagram. The 4-pin power supply socket available at the rear of a CD-ROM player is meant for +5V, ground (two middle pins) and +12V inputs. The power supply can be easily derived using a conventional power supply circuit as shown in the figure. If you have an external CD-ROM drive, it can be simply plugged into the mains since it has self-contained power supply circuit inside.

While there may be minor differences amongst the available CD-ROM drives’ external controls, a typical drive’s controls are shown in the figure here. Please ensure that a proper power supply connector available from computer spare parts vendor is used for connection to CD-ROM drive. To identify +5V and +12V pins on the drive connector, please note that in the computer +12V is routed using a yellow wire and for +5V a red wire is used, while for ground black wires are used with the supply connector. Once the power supply has been connected correctly, you will notice that LED indicator on the drive starts flashing. Now the digital audio CD can be loaded after pushing the eject button. A second push of the same button causes retraction of CD carriage into the drive. One can change the track (song) on the CD using play switch on the CD-ROM drive.

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Non Switching Current Drive Amplifiers

Non-Switching Amplifiers

Most of the distortion in Class-B is crossover distortion, and results from gain changes in the output stage as the power devices turn on and off. Several researchers have attempted to avoid this by ensuring that each device is clamped to pass a certain minimum current at all times. This approach has certainly been exploited commercially, but few technical details have been published. It is not intuitively obvious (to me, anyway) that stopping the diminishing device current in its tracks will give less crossover distortion .

Current-Drive Amplifiers

Almost all power amplifiers aspire to be voltage sources of zero output impedance. This minimizes frequency-response variations caused by the peaks and dips of the impedance curve, and gives a universal amplifier that can drive any loudspeaker directly.

The opposite approach is an amplifier with a suffi ciently high output impedance to act as a constant-current source. This eliminates some problems – such as rising voice-coil resistance with heat dissipation – but introduces others such as control of the cone resonance. Current amplifiers therefore appear to be only of use with active crossovers and velocity feedback from the cone . It is relatively simple to design an amplifier with any desired output impedance (even a negative one), and so any compromise between voltage and current drive is attainable. The snag is that loudspeakers are universally designed to be driven by voltage sources, and higher amplifier impedances demand tailoring to specifi c speaker types

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