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.

8- DC/DC converter:
it used a simple 7806 regulator and two coupling capacitors (see application not on the datasheet of any L78XX regulators)

9- Assempling the connectors:

the jack to RCA adaptor is assembled on the rear of the computer case.

10- Test:

Finally we can start the computer, listening to an audio file and see the result.

 

Replace CFL with white LEDs

The CFL lamps are very used these days as a solution for economic lights. In TUNISIA the good quality lamps are relatively expensive between 6 TND and 12 TND (about 4$ to 9$). At my house I have not good expeience with this type of lamps most of them are broken after one or two years of working.

Broken CFL in my stock

To have more information about CFL you can see the following good link:

http://www.pavouk.org/hw/lamp/en_index.html

As I have many lightening points I have decided to convert the CFL with LEDs to see the lightening power result. One CFL is replaced with 12 LEDs, one LED cost 0.2TND so one CFL is replaced with LEDs cost 1.4TND (1$) the other electronic components are picked from other electronic devices I already have in my workshop stock and also from the CFL circuit itself.

Powering LEDs from the main 220V source this is an easy manipulation by finding schematics on "google" (for example). I have used the following schematic designed by myself to power 12 LEDs:

Make attention this circuit is connected directly to the dangerous main source. Don't touch any point of the circuit before disconnecting the circuit from source.

1- we start by opening the CFL lamp:

2- Desolder and separate the three main parts of the lamp

We need only the two parts marked with red arrows

 3- By examining the circuit we can see that a capacitor is broken, this a common failure on this type of lapms with capcitors fail:

 4- I have cutted a circular part of wood that can be assembled on the front plastic part. this wood disc will be used to place the LEDs

5- after that we make the driver circuit and place the LEDs on the wood disc:

 6- we solder the parts together:

7- we assemble the parts together and we have the final LED lamp:

8- Power the LED lamp on the main 220V source and the lamp is lightening very good:

9- We can put our lamp with a milli-ammeter to see the current consumption, we can read 22.48mA this give us a lamp of only 4W (this is economic lamp!!!).

To be honnest the lightening is not very powerful, this can be used for low lightening needs. I have used them in my stairs, showroom and hallway.