Saturday, January 10, 2015

Motion-controlled non-intrusive bed light

Don't you hate it when your significant other wakes up in the middle of the night and turns on the bedroom light?
If she also happens to stumble upon some furniture pieces in the process it makes it even more fun.

Just kidding, engineers don't have girlfriends.

Problem 2 was solved by having a remote control for the light, on the nightstand.

Every person should come with a remote

This turns on a lamp behind the bed. The lamp was turned over so it only produces a diffuse light:

Looks nice, when it's not raining
For the first issue (not seeing where stuff is) I reused some LED strip I had lying around, taped it under the bed and added two motion sensors.

The motion sensors turn the lights on when one someone steps near the bed (or gets out of it) and the lights stay on for about 20 seconds.

LED strip going around the underside and one of the motion sensors

Total cost of the project should be less than 25 USD/EUR:
- LED strip - 5-15$.
- power supply - 1-5$, unless you already have one 7,5-12V supply around
- motion sensors - 1-2$ each
- Darlington power transistor - <1$
- cables, tape, time

Ghetto remote Wii sensor bar

We had some guests coming over and thought of setting up the Wii to work with a cheap beamer. Oh, and only had a few hours to do that.

However, the cable for the Wii sensor bar is only around 3m and it was required to go about 6m. I can either cut it away, add some wire and be done or try to make it work from a distance.

Here's how to make your own remote bar with no damage to the original, in just a few minutes.

You need a glue gun, some resistors (2x100 ohms + 20 ohms or 120 ohms + 100 ohms) some wire and some pins. You also need a 12V supply to power everything up, I had a motorcycle battery in for the winter.

Power supply project - part 2

This is a follow-up to in which I was trying to fix a car battery charger but ended going down the 'feature creep' path.

It still contains two power supplies, one is 0-17V, the other one 7-25V. Unfortunately the input voltage is limited to 19V, which means the maximum output is lower than that. I would probably dump the transformer and put a 24V/2A HP printer power supply instead.

The additions are two sets of binding posts and a power switch, better noise handling (star ground) and a new firmware.

The top LCD display shows the voltage and current for the first power supply, with a nice 'clock' graph for the voltage and a thick horizontal bar graph for the current.
This is duplicated for the second supply.
The microcontroller also has a graph mode that can display any value over time, auto-scaled. Since the button to access that is on the back of the board I don't use it very often.

Sunday, January 4, 2015

Toshiba 32TL868 LED 3D TV teardown

See last Toshiba posts for firmware reverse-engineering analysis.
TL;DR version: it would take too long to come up with a useful firmware mod. I'm missing the toolchain, complete source code, compilation instructions, libraries, hardware architecture, ...

In the meantime, I did take the TV apart to fix a broken stand-off.