VCD player with built-in amplifier

lorant

VCD player with built-in amplifier [Copy link]

For a long time, I have always felt unsatisfied when using VCD players, because VCD players do not have their own amplifiers. When playing discs, in addition to speakers, they must be equipped with a TV or an amplifier, so it is extremely troublesome to use.

I have a VCP-N28K VCD player produced by Wanlida in the early days, and I have added a simple stereo amplifier circuit to it, which is extremely practical.

The power amplifier circuit adopts the "LM1894+LM1875" scheme, which has the following characteristics:

1. The transformer is used alone, completely separated from the VCD machine, but a power plug line is used at the same time.

2. The L and R audio output sockets of the VCD machine are also used as the input interface of the power amplifier.

3. A single-link volume potentiometer is used, and the volume of each channel is adjusted separately.

4. A switch is added to the signal input end. In conjunction with the L/R key of the VCD machine, the two-channel signal can be mixed or the two channels of the power amplifier can simultaneously amplify the single channel signal output by the VCD machine; if it is disconnected, the left and right channels are separated. This switch is particularly practical in teaching and accompaniment appreciation.

5. The power amplifier circuit is connected as a current negative feedback DC power amplifier, which has good effect and is easy to make.

6. The power amplifier circuit board, rectifier filter board, and transformer are all shielded to effectively prevent mutual interference.

Adjust RP (RP′) to minimize the high-frequency loss of playback and achieve obvious noise reduction effect. In addition, if the signal is too strong, a 5-15kΩ metal film resistor can be connected in series at the signal input end to solve the problem.

All knobs and switches are installed on the rear panel.