Conny likes to fall asleep with some light on. I dislike having to wait until she's gone late at night, just to switch off her bedside light. I dislike having an energy-wasting halogene 25W burning all night long even more, not to mention the temperature problems with the transformer base buried in stuffed animals.

The solution: teach her something! So we repurposed an old broken desk lamp carcass, I taught her how to solder, programmed a 12f629 PIC and we combined the above with sufficiently many white LEDs and some recycled laptop Li-Ion cells into an auto-off bed light: Press the button when off, and you get 18 min of light. Press the button when the light is on, and the light goes off. Simple, neat, efficient. As a bonus the lamp body is black, Just Like It Should Be.

The circuit is trivially simple, the diagram follows and the PIC code (also boringly simple) is here (plus the auxiliary delay library).


The diagram is not complete in two particulars: I used a 4.5mm plug with a builtin bypass switch to isolate the battery when charging (don't want to blow the LEDs and/or PIC when my intelligent charger feeds the LiIon), and I repurposed the original lamp switch as an extra "general disconnect". BSTS.

Great care should be taken to avoid shorting or annoying the three 2000+mAh cells in any way - unless you like to play with fire extinguishers.

 2008_02_14-nachtlicht-brain.jpg  2008_02_14-nachtlicht-leds.jpg  2008_02_14-nachtlicht-löterei.jpg 2008_02_14-conny-nachtlicht-löten.jpg 2008_02_14-nachtlicht-fertig.jpg  2008_02_14-nachtlicht-in-action.jpg

Conny did all the soldering apart from one or two small fixes and the LED interconnections. Well done.

[ published on Mon 18.02.2008 00:00 | filed in interests/tinkering | ]

I enjoy technical challenges...if and when I succeed eventually. This posting may be a technical challenge for you, but watch me not care. Some of you may appreciate the information and that's good enough for me. So, if you're interested in homegrown MP3 music boxes, Linux on Netvistas, PIC microprocessors, RS-232, infrared remote controls, and what an obtuse idiot I occasionally am, read on!

(As always I also hand out the involved source code, which might come handy if you want to build something similar.)
click here for the rest of the story...

[ published on Mon 17.12.2007 13:30 | filed in interests/tinkering | ]

This was actually quite fun to build, a quickly gratifying small job: how do you drive an LED from very little voltage (as in, a single 1.5V cell)? You can't do it directly because leds need more voltage (at least 1.6V for reds, above 3.0V for many/most whites).

So you need some booster circuit. Clive has a nice set of instructions for making what he calls a "Joule Thief", a simple inverter with three parts only: a centre-tapped inductor, a resistor and a transistor (He also has articles on other Must-Have Cool Things, like how to make a USB-powered turd).

For the ham-fisted among us, these guys show how to build the same setup with larger-sized parts.

I had a few minutes of nothing better to do this arvo, and built three variants with a fat 10mm white led: one hand-wound largish coil (2cm dia), one salvaged coil of similar size, and one smaller hand-wound one (0.9cm dia) with which the circuit wouldn't light up continuously.

For the adventurous, Dick Cappel has another set of really nice pages on similar projects, like the Rusty Nail LED inverter.

[ published on Sun 04.11.2007 21:03 | filed in interests/tinkering | ]

Daylight is fine, but darkness isn't to be frowned at. If you have LEDs, that is.
click here for the rest of the story...

[ published on Sun 07.10.2007 01:20 | filed in interests/tinkering | ]

Rob gave me a 1GB clonepod. Its Chinese designers made a number of...questionable design decisions, and as a result the player was somewhat broken when I got it.
click here for the rest of the story...

[ published on Sun 07.10.2007 00:51 | filed in interests/tinkering | ]

A few months ago, I made a simple PIC-based POV toy for my daughter. Here are some building notes, photos and code of course.
click here for the rest of the story...

[ published on Tue 02.10.2007 13:12 | filed in interests/tinkering | ]

Silastic RTV sealant is very useful, even if a third of the tube has already vulcanized...
click here for the rest of the story...

[ published on Sat 22.09.2007 17:56 | filed in interests/tinkering | ]

Having a 4 channel oscilloscope makes tinkering so much easier. Now I can look at four incomprehensible and unexplainable voltages at the same time!
click here for the rest of the story...

[ published on Mon 09.07.2007 21:15 | filed in interests/tinkering | ] hear how my friend rob is spending a lot of time in the gym. My character is already fucked, so why waste time in the gym? It's spent way more productively with soldering iron in one hand and a datasheet printout in the other ;-)

Latest example: I talked to rob earlier this evening (about 3.5hrs ago), and he asked me how hard it would be to make a Hardcore Gym Timer, so that he can keep his "8 second blast/12 second slow" training regime precisely.
click here for the rest of the story...

[ published on Sat 07.07.2007 00:55 | filed in interests/tinkering | ]

"Innsbruck, Ich muß Dich lassen"...viel schlimmere Barock-musi gibts nicht. Ein guter Grund, das Gedudel als Türglocken-Melodei zu verwurschten. Weil es soll ja nicht gut und wohlig klingen, sondern laut und nervig damit a) ich aufkreuch und zur Tür gehe und b) die Wartenden sich möglichst gleich ohne meine Mithilfe dazu entscheiden daß sie sich schleichen. Weil mei home is mei kastl, da sind nur wenige besondere Leute willkommen. In diesem Sinne also eine perfekte Wahl. Wie ich das verbrochen hab, erzähl ich weiter unten.
click here for the rest of the story...

[ published on Wed 04.07.2007 01:20 | filed in interests/tinkering | ]

Somehow I don't think I'll run out of caps anytime soon.


As I've been tinkering a little bit with electronics and microcontrollers recently, some more components were required. I dislike wasting money. And I like bargains.

Somebody sold off his stuff by the kilo, after retiring from an electronics repair career. All bandoleered, also mostly labelled and well mixed: a few strips of transistors and filters/ceramic resonators, resistors, a pile of chokes/inductors, some tantalums, a pile of ceramic caps, a big pile of film caps and a bloody huge pile of electrolytics. I said well mixed: all common values well represented. Ah yes, and more fuse holders than I'll ever need.

4.7kg of gear, for a whopping total of AU$80. I'm pretty pleased. But the sorting is a pain.

[ published on Sat 30.06.2007 20:40 | filed in interests/tinkering | ]

I've got a new toy: a Tektronix 2246 ModA, for about $500 (incl. shipping from the UK). It's really nice (100MHz, 4 channels, analog but microcontrollered, hence nice measurement and cursor features).

Current project: making a very obnoxious and loud doorbell with a PIC. I came up with the necessary microsecond-precision delay routines and the remaining frequency generation stuff, and a bit of perl took care of eating a MIDI file and barfing out suitable frequency and duration information in PIC assembler.

The last insanely horrible tune I've been trialling: "Innsbruck, ich muß dich lassen". Sounds perfectly ghastly when a cheap piezo is squarewave-squealing its guts out. I'm also thinking about using "Tirol isch lei oans" just to remind me why I'm here and not there.

Here's a pic of the latest test setup: I'm currently learning how to use an inductor to boost voltages (and how a common collector amplifier works). Messy but fun.

[ published on Wed 28.03.2007 02:33 | filed in interests/tinkering | ]

...cupboard doors into desks, IBM Thinclients into music boxes and all politicians everywhere into dead politicians. I'm all for it, and I did my part for the doors and the music player. (And just for the bloody record, let's get rid of all the governments, too. Yay for Anarchy! I'm in a bad mood today, as you can surely tell.)
click here for the rest of the story...

[ published on Sun 11.03.2007 15:35 | filed in interests/tinkering | ]

Here's some recent projects/happenings. For my new RC plane I needed reasonable charging facilities, because most trickle chargers like the one I got with the RC gear are trash. So after some thinking about building my own charge controller (not too tricky but time-consuming) I bit the bullet and bought this SJ Propo Swallow Advance charger: a very nice bit of equipment, charges pretty much anything from Lead-Acid to Li-Po intelligently, and with nice options. $90, so not exactly breaking the bank.

But the Swallow is DC only, 11-15V, good for taking with you in the car, bad for at home. I hate wallwarts. So I need: DC, preferrably 12V at 3-5A. But I have: loads of lousy underpowered wallwarts (bad) and loads of old garbage (good). Because the old garbage contains the innards of a few Sun SCSI enclosures, some of which came with brilliant fanless Sony-made switching PSUs. APS-28: old, silent, solid, juicy and saucy :-)

Time for the tinker: it simply took a few galvanised nails, some foam and a bit of soldering to convert the Molex outlets to posts for crocodile clamps. (There is extra insulation behind the foam, but the sparkies wouldn't be too happy with the design. Screw 'em!)

 2007_03_01-swallow-psu-bare.jpg  2007_03_01-swallow-psu.jpg

That PSU now also replaces three wallwarts, which makes me really happy. I fabricated some custom charging leads from scrap (old wires, some computer connectors, crocodile clamps from rotten test leads etc.) next: one 12V lead for the Yaesu VX5R which has its own charge controller (Li-Ion) and a tiny plug, one 12V fat plug for the CDMA phone's charger-stand (with its own controller).

The fat plug also works with the cordless drill, now and only after I gutted the drill charger stand: first I connected the Swallow to that, but the stand actually contains a few resistors for trickle charging. The Swallow blasted a few Amps at about 19V across that, the resistor got a tiny little bit hot, the stand plastic started growing surrealistic in shape and I quickly stopped things before the Magic Smoke got out. Now: gutless stand, brains in the charger. Me happy.

Another recent successful tinkerproject was modding Guntis' radio: he wanted a remote PTT switch to connect to his small speaker-mike sitting on his shoulder, just like the setup I've used for the last two years. (My new in-helmet setup was tested on Sunday and works superbly.) So I hunted up parts, traced the wiring in his speakermike and Simply Dit It. First I rewired the speakermike to activate on the PTT switch, and then I built a new remote PTT switch from scratch.

Here's the switch I made for him: 100% recycled components! :-)

 2007_02_25-guntis-ptt-side.jpg  2007_02_25-guntis-ptt.jpg

The switch is a leftover from a dead computer mouse that I desoldered, the cable with conveniently moulded-on mono plug comes from a first-crap-then-defunct $50 "stereo system", the button (for improved tactile feedback with gloves) is from the sewing kit my great-aunt left me, and the velcro was a leftover from some other project. Even the idea for the switch is recycled: this guy had it first :-) (Ok, solder, superglue and shrinktube were new. Sue me.)

And the next projects are already on the horizon: exploring the wonderful world of PIC microcontrollers. These things are cool! (I recently spent about $250 on a better multimeter and a bunch of chips, and may soon spend another up-to-$800 on an oscilloscope. Learning electronics is fun, but getting a reasonable set of tools is not -- for a money-concious person like me.)

Here's my first pic circuit: it toggles the led state on every switch activation, debounced in software. Looks like nothing, better stuff to follow soon because I've got shitloads of wacky ideas that I want to implement...

[ published on Thu 01.03.2007 23:21 | filed in interests/tinkering | ]

newer... older...

Debian Silver Server
© Alexander Zangerl