FireFly Jam Jar

I wanted to build a night-lamp for Luísa, something a bit less "spooky" than a blue IKEA Spöka that she has. I also wanted to be able to charge just by placing it in the sun (even there isn't much of that up here)...
I went back to my stack of old ATTiny15L and designed a circuit with four LEDs connected in a particular way that only used 3 pins to lit each of them. The other two measure external light (light on when it is dark) and battery (low bat... do nothing be very very still).
I got some jam jars and some Yellow/Amber LEDs and started programming, for the battery I selected a 3.6V 50mAh NiCad (i.e. junk hanging around) and the battery charger was a two transistor current limiter but after some tries I settled with a simple schottky diode from the panel to the battery.



The idea of the project is that when night falls (or lights out) the light goes on for about an hour hopping from one light to the other with different ratios of fade-in and fade-out. This hopefully will induce a sleepy feeling (like candles... by the way.. simulating four candles is also possible)
The schematic is the same as for the reindeer ball project, but this time I went "all the way" to a PCB FAB. I still have to wait for it to come but it looks nice in the preview.



It is my first "non-rectangular" board and actually my first milled board. We'll see how this project will look like in the end...

Alex OpenTherm interface for JeeNode

Alex requested a "quick and dirty prototype" for his Opentherm JeeNode interface. He has more details on the "substance" here and here. I just made the boards, it is all his design (boards plural, the first one was wrongly mirrored, b.t.w. it is the wrong one you see on the pictures).
I followed the usual toner transfer method, and just works, HEMA photo paper is the best! The second board is not so pretty.... but at least it is correct (no photos of this one though).
The schematics are on Alex's site but here's my second try at the schematics also:


Here a detail of the board where you can see some "over etching":

Bird-O-Matic

Pedro asked me, some time ago, to do a collaboration project with a good friend of his.
The idea for the installation art project was the story "The Nightingale" from H.C. Andersen, the idea was to build/make a talking bird of sorts. Our initial plans had to change somewhat substantially... here's what we did:

My part, was to design and build the electronics that would "make the bird sing", we already had the bird's voice in a mp3 track (a danish Nightingale!!), we just needed something to play it. The original idea was to have a bird (just like in the story), but one of the places was an open air installation, so a bird cage seemed a better option.

The first constrain was time, we had only two months for doing the first "bird-o-matic". We gathered a PIR Sensor, a MP3 Player, and a LM386 amplifier IC from Solarbotics.
We wanted a reasonable sound volume so we chose a 9V battery to power the circuit, this is challenge because these batteries do not have a big capacity (max about 1000mAh) and we still wanted to play for some time without replacing the battery. This also excluded from the start using an Arduino as they consume a lot of current even if you manage to put it in standby.
I decided to use a simple monostable (LMC555) triggered by the PIR sensor that would activate the MP3 player and amplifier for a reasonable time (enough to play the nightingale sound). I used low-power MOSFETs for the power switching and one as inverter.
The first build used a LM78L05 but these have a very high quiescent current (~4mA), 10x more than the PIR sensor alone(~350uA)! The second choice was the LM2950 with only 40uA without load (increases to about the double with load) The LMC555 also has a lower quiescent current when operated at 5V (100uA) when compared to 9V (~160uA), and orders of magnitude lower than his "high power" counterpart the LM555.
Still the total current in standby was lower that 600uA, this would give 2000 hours in standby!
Playing... well "you can't make an omelet without breaking some eggs", the MP3 player consumed about 80mA and the LM386 another 80mA, giving a total play time of about 6 hours, still quite good if you think that the track was only 20 seconds... that is about 1100 times... it also exceeds the LM2950 maximum current by 50% but it works until it is too hot then the thermal shutdown "kills the bird" (battery saving on the cheap).
Here is the schematic:

Here is a close up of the inside of the bird cage:

Here a photo of the first prototype:

New Boards arrived!

A month or so ago I bought a development kit of GreenPak from Silego. The parts appear to be very powerful for simple control tasks, I have a small Switch Mode Power Supply project but I wanted to try it out on a breadboard before committing to a full PCB.
The parts are tiny tiny and an adapter to DIP 8 was needed. I sent my mini design to lean and my boards are here! Here's the result!