AdriZ’s electronics blog

The goal is just to give us cupboards some light with white LEDs.
There’s three distinctive parts:

• a power supply
• one or several bars of white LEDs
• a switch (model specific for doors)

Power supply

We used a simple 230V (I live in France) to 12V transformer for lighting (because it’s cheap and easy to fix). We just add a diode rectifier and a capacitor to convert alternating current in direct current.

One thing we didn’t know before: this sort of lighting transformer output a 30 KHz alternating current. The frequency is raised to reduce the light fluttering and to raise the bulb lifetime. This is not a problem for our application, but when I tried to measure output voltage with my cheap multimeter, it displayed 0V ! This is because cheap multimeter are not designed (and failed) to measure a 30 KHz alternating current.

LEDs bar

To fix LEDs and hide cables, we used a little U-shaped cable trough.

It is made of parallel branches of 3 LEDs and one resistor in series.

Then the system is upgradable just by adding identical branches.

Schematic

Cupboard Lighting - Schematic

Photos

Cupboard opened

Inside cupboard

Grounds

I’ve got an audio system that allows to listen my music collection in my living-room as well in my kitchen.

In the linving-room, my computer, wired to my home theater, read the music via iTunes. The computer also stream the music via WiFi to an Airport Export located in the kitchen.

Regularly, we listen music randomly and would like to know what is the music we are listening and eventually change the music or the volume. But when we are sitting down in the kitchen, we have to stand up and go to the living-room to see the artist / music names. But humans are lazy, and technology is often used to keep us lazy. This is why I had the idea to create a device, located in my kitchen and wirelessly connected to the iMac, which will display music informations and have few buttons to remote control iTunes.

Hardware

Core

The device deals with an Arduino board, hence the name iTunes2Arduino.

Arduino is an open-source electronics platform based on Atmel AVR micro-controller.

Arduino Diecimila (USB)

The standard Arduino used an USB connection to talk with the computer. To connect wirelessly I used the Arduino BT, which is a Bluetooth version of the Arduino platform.

For more information about Arduino, you can visit the official web site http://arduino.cc

Display

Informations are actually displayed on an 1×16 characters LCD (model Seiko M16410A). This is a LCD compatible with the Hitachi HD44780 standard.

It just has a particularity: it is driven like a 2×8 characters LCD (in fact the two lines are side by side).

Thank’s to the Hitachi HD44780 standard, the software can be easily adapted to drive other alpha-num LCD (I plan to connect a bigger one).

Buttons

iTunes2Arduino is actually a prototype, buttons are planned but the software doesn’t use them yet. I also would like to use touch buttons with a slide bar for volume control.

Battery

This is also a future improvement. I plan to add a charger system which can be disconnected / reconnected any time (like mobile devices). With a such system, the iTunes2Arduino will be available everywhere in my house without being bothered by wires.

Arduino to LCD connection

Arduino to LCD connection

Software

Micro-controller software

[ To come ]

Computer software

[ To come ]

Back panel

We had an old used TV which had no longer sound card. Solution: make an audio power amp.

Specifications:
• output power: 2 x 10 W (on a 4 Ω load)
• supply power voltage: 8 to 28 V
• power amp class: AB
• volume control
• 2 bands equalizer
• pan control

The scheme can be divided in two parts:

• Power amp
  The power amplification is realized by a integrated circuit TDA2009. The scheme for the power amp part is the one given in the Figure 13 of the TDA2009 datasheet (without the sound control part).
• Sound control
  It is composed of a 2 bands passive equalizer, a simple volume control and a potentiometer for balance.

2x10w Audio Power Amp - Schematic

Schematic (pdf version)

Back panel

Inside

Inside, closer

This is a simple laboratory power supply made with my girlfriend Marjorie Limousi, when we was student. The power supply is one of the most important device to start electronics and this was one of our first finished electronics project.

Pink Power - Front panel

Requirements was:
• 2 channels
• separated grounds
• regulated voltage
• output voltage: 2 V to 22 V

The scheme is standard:
• a power transformer
• diode bridges
• decoupling capacitors
• adjustable regulators

There’s just a particularity. We were students, with not a lot of money, so almost all of the device was made with recovery components! Due to the poor choice of components, we had to use some tricks. Thus, on the scheme, on the top channel you can see some diodes in series, and in the bottom channel you can see two diode bridges in series. They are used to drop out the voltage to avoid high voltage on 4700 uF capacitors (which have a low maximum voltage).

Pink Power - Schematic

The box is handmade in wood and pink painted.

Back panel

Inside... handcrafted.