Nouri DIY: Adding VU-Meter to your computer

From a SONY double tape decks with model number "SONY TC-W230" I have picked a nice LCD VU-meter. I have decided to add it to my computer tower case. the following steps explain how to do this.

1- Overview of the SONY VU-Meter:

this is based on IC lablelled CXD1017 (impossible to find a datasheet) on the printed circuit it is easy to identify the connected wires (second photo red rectangle) so we can see:
* RES: not used.
* -6V: used for the retro-lightening lamp.
* LIN: Left channel input.
* GND: Ground.
* RIN: Right channel input.
* +6V: used for powering the circuit and for the retro-lightenning lamp.

The first think that I have done is to look for the schematic circuit of this HIFI equipment and after a long time I have filnally found the service manual. So the following photo shows the VU-Meter schematic diagram:

2- Block Diagram of the project:
To integrate this circuit in the computer case we have to provide two thinks:
* the 6V power source: this can be done by adding a DC/DC converter using the 12V from the PSU.
* the audio channels inputs: from the sound card outputs.
This is a general block diagram of the realization:

3- Replacing lamps:
The lapms used in the VU-Meter to lighten the LCD consume a lot of current this why they are powered by a symetric source -6V and 6V. I have decided to replace them with 4 white LEDS.

On the VU-meter rear cover I have also added an aluminum cover to enchance the LEDs lightening

4- Test the VU-Meter before:

Before I have decided to mount the VU-Meter I have decided to test it because I have picked it from salvaged audio equipement and I don't know if it function or not.

after powering it with 6V (from my adjustable power supply) and I have connected the audio inputs the result was good.

5- Prepare the place for the VU-Meter:
I have opened the computer case and prepare the place to receive the VU-Meter.

6- Place the VU-Meter:

know I have placed the VU-Meter in the fron part of the computer case.

7- The Jack to RCA adaptor:

As my computer is connected the AUX input of my HI-FI system via RCA connectors I have to add an adaptor to convert the audio channel from jack connector of the computer sound card to RCA connectors going to the HI-FI system. this circuit is a simple parallel connexion between jack connector and RCA connectors.