Sunday, February 27, 2011

The Final Arduino Kitchen Timer

Kitchen-Timers have a durability which is only slightly bigger than the warranty of the device. It doesn't matter if you buy a cheap one or an expensive. They initiate self-destruction after one year (IKEA, WMF, Zyliss, No-Name... I tried them all) . That's just my personal experience and this is also the reason, why I decided to build my own kitchen-timer.
...and it's name shall be "The FAKT".

I could not find a suitable solution for me on the web, so I have to engineer by myself this time.
Because I didn't want to reinvent the wheel, I choose Arduino as suitable platform. There are enough libraries and documentation and examples available. The board is cheap and very friendly for prototyping.

My requirements for the FAKT are:
- Simple to use with just one rotary-encoder and a LCD-display
- A loud beeping-tone or a melody indicates when the time is expired
- A low power-consumption
- Small dimensions
- Simple to build
- Simple to code. Reuse as much code as possible.
- Cheap hardware

The first firmware-version is working fine, but there are still some open issues. Power-saving should be implemented and my inner-voice told me to switch to an 3.3V-based Arduino-board. I think I will do so. Otherwise I have to destroy my Uno and I don't want to do that. I'm thinking about an Arduino Pro Mini. This will make it also fit in a smaller housing.

The LCD was surprisingly easy to integrate. I used an existing library called DogLcd.
The rotary-encoder is interrupt controlled based on example code from, but I'm still not satisfied with debouncing and step-regognition. Sound is played via two PWM-pins to get a higher volume. This is not optimal and I have to find a different solution, if I switch to 3.3V power-supply.

GORF !!!

The GORF is a 8-step midi-sequencer by Vacoloco. I build this device some month ago, but never had the time to post it here. The PCB is well designed and all components are mounted on it in a very space-saving way. To polish my grey housing a little bit, I put stickers on it which showing the logo from the Austrian TV-station ORF. The "G" in the logo comes from their payment-division called GIS (yes - everyone with a TV has to pay for the public-television in Austria, even if he is just watching the private-channels). But the name of the sequencer is from an 80ies video-game.

Here is a video showing the Gorf controlling my SX-150 via the CV from the MidiVox:

It's very easy and intuitive to program the GORF. You can also change and send Midi-CC.
When you connect your MIDI-keyboard to the gorf, you can transpose the programmed patterns.

There is still a problem in the GORF-firmware when using another bank than the first. The firmware if available, but you need an AVR-programmer to change it. I installed the programming-interface and the MIDI-In and MIDI-Out.

Here is a picture of the plain PCB and some nice close-ups:

MidiVox SX-150 Mod

Narbotic posted a nice mod for the Gakken SX-150. As you may already guess, I could not resist to try it out. It's a very small modification on the arduino-based MidiVox and because it worked so well, I decided to build everything in a eurobox. The MidiVox is connected to the stylus of the SX-150 and control it via CV.

Gameboy Bluetooth Mod

I had the idea to enable wireless audio on the gameboy in a very simple and cheap way. For that purpose I used a pair of small a2dp-bluetooth devices.

The sender is mounted with a velcro-strip on my DMG. This is a easy way to remove the device, if not needed and you don't have to hassle with space in your Gameboy.

For the receiver I decided to remove the PCB from the original housing, because it cannot be charged during audio-streaming. So I removed the battery and add permanent power-supply and for a better handling I also exchanged the buttons with bigger-ones. With the buttons you can pair another bluetooth-device, change the volume or skip tracks (if supported on the remote side).

The system works fine for me, but as I expected, there is a audio-latency about a half second.
I can't wait to test the system on stage :D

Saturday, February 26, 2011

Instant failing @ the direct toner method

Today it was beautiful outside.
The first day in spring with blue sky and bright sunshine.
Today was a waste of time.
Today was a constant fail.

In the morning I was fully motivated to give it a try on etching some PCB's with the "direct toner method". I tried it so many times with my iron using different temperatures and techniques to bring the layout from the sheets of my "reichelt catalogue" to the coppered-PCB's. Even letting the PCB an hour in the water to soak the paper well, did not work. I expected that this method would not work on the first try - oh yes. So I printed many sheets with a HP-Laserprinter in advance - just to be on the save side...
It was a disaster.
Every time I reached step 3: Goto step 1. Groundhog Day.

But who's to blame?
- my cheapo electric iron from TCM?
- the laserprinter or it's bad ink?
- the author of this method who is using a modded laminator and laughing at people with an iron?
- globalisation?
- al-Qaida?
- ...or at least my two left hand's?

I have no idea and yes - I'm a "bit" frustrated :-/

I got two PCB's which looked acceptable and maybe just need little corrections, so I decided to continue. They looked like this:

But before starting etching, I tried to remove the rest of the paper with boiling water and soap. This worked fine using my rubber-gloves without removing the ink to much. Then I started with the etching:

...and the result after removing the ink with Acetone looked like this:

To sum up everything I come to the following conclusions:
If the ink could be brought to the PCB in a very clean way, the etching is no big problem. Etching only works, if _all_ the paper is removed (even from the strip lines!). So the main problem in the whole method is to iron the ink to the PCB. The advantage on this method is, that you can start all over again, if that doesn't work on the first(haha) attempt (each try doesn't cost you money - just a little Acetone and time). But if you have problems in constant results you would fail like me.
I invested a whole day without satisfied results.