Necromancer's notes

I had this router around for quite a long time, but unfortunately it sucked at some points.
1. The clock bug. It’s 200Mhz, not 240, the clock’s off and the result is usb 1.1 hangups. Luckily this is cured by installing a 2.0 hub, to do transaction translation
2. Memory. 16mb is a not enough! Esapecially with the leaking wl driver. b43 seems quite greedy as well. The trunk builds of OpenWRT did not work for me any more, so…
I was of for an upgrade.
Continue reading “ASUS wl520-gU: RAM upgrade” →

Just received this thingie. I was attracted by the price, avaliability of kernel sources and the fact I really needed an embedded PC for my needs. Once I got it, the dongle with usb and ethernet caught my attention so I disassembled it. And… what do I see?

Continue reading “WonderMedia WM8650: Adding an uart” →

I got quite a bunch of these thingies some time ago, so it was just the time to get the fun started. At least I needed a car charger for my tablet badly. The wall plug is said to provide 9 volts up to 2,5 Amps. So GS6300 3 Amp thing was just what I needed.
The datasheet for the chip sucked: really little detail and only one application circuit. Luckily, the application circuit was quite simple to understand, so with minor modifications I made a small power adaptor for my flytouch II tablet.

Hints: Make sure you use the right core for the inductance: if you pick the wrong core, you’ll get GS6300 to heat up pretty fast at some 500-600mA consumption.
If you get the diode with the wrong trr (reverse recovery time), you’ll get it to overheat and won’t get enough current.
At first I used a 10k POT to adjust the output voltage and got it to be VERY unstable. 1k POT solved the problem.
Tab is connected to the GND pin, so make sure you have some nice’n’big ground polygons do dissipate all the heat, unless you want to attach a heatsink. At big currents it heats up. (a charging tablet + max brightness screen + a 3g modem plugged into the tablet).
There is the photo of the assembled thingie:

Since I didn’t have the car’s smoke’o’plug around, I wired the raw voltage from a 5v dc-dc stepdown I had around.

Well, It relly rocks when you have an access to a laser cutter and have some spare acrylic. Some time ago I’ve done this test-tube holder I use in my lab.

Instead of the actual test-tubes I use bottles from ‘bifidum bacterinum’ I used to take whenever I got my stomach screwed by antibiotics. Therefore, I have a sh*tload of ’em. So there goes a photo of the thing:

The source code for the OpenSCAD project is below, licensed under the beer-ware license.

rows=2;
cols=5;
spacing=2;
borderspace_w = 4;
borderspace_l   =  20;
radius=8.5;
drill_via=1.6;
delta=0.1;

TARGET=2;
//////////////////////////

length  =  borderspace_l*2 +  spacing + (radius*2+spacing) * cols;
width   =  borderspace_w*2 + spacing + (radius*2+spacing) * rows;

module vials(rows,cols,spacing,radius, borderspace_l, borderspace_w, shift)
{
length  =  borderspace_l*2 +  spacing + (radius*2+spacing) * cols;
width   =  borderspace_w*2 + spacing + (radius*2+spacing) * rows;
echo("Vial holder: length: ",length, "width:", width);
difference(){
	for (j=[0:rows-1])
	{

	for (i=[0:cols-1+ ( j % 2)])
		{
		#translate(
			[
			borderspace_w +radius+spacing + (radius*2+spacing)*j,
			-shift * (j %2 )  + borderspace_l  +radius+spacing + (radius*2+spacing)*i
			]
			) circle(radius);

		}
	}
}
}

difference()
{
	square([width,length]);
	# translate ([width/4,borderspace_l/3])circle(drill_via);
	# translate ([3*width/4,borderspace_l/3])circle(drill_via);
	# translate ([width/4,length-borderspace_l/3])circle(drill_via);
	# translate ([3*width/4,length-borderspace_l/3])circle(drill_via);

	# translate ([2*width/20,length/2-radius-spacing/2])circle(drill_via);
	# translate ([2*width/20,length/2+radius+spacing/2])circle(drill_via);
	# translate ([18*width/20,length/2])circle(drill_via);
}

if ( TARGET==1 )
{
	translate([width+delta,0]) difference(){
	square([width,length]);
	# vials(rows,cols,spacing,radius, borderspace_l, borderspace_w, radius);
	# translate ([width/4,borderspace_l/3])circle(drill_via);
	# translate ([3*width/4,borderspace_l/3])circle(drill_via);
	# translate ([width/4,length-borderspace_l/3])circle(drill_via);
	# translate ([3*width/4,length-borderspace_l/3])circle(drill_via);

	# translate ([2*width/20,length/2-radius-spacing/2])circle(drill_via);
	# translate ([2*width/20,length/2+radius+spacing/2])circle(drill_via);
	# translate ([18*width/20,length/2])circle(drill_via);

	}
}
else
{
	translate([0,0,15]) difference(){
	square([width,length]);
	# vials(rows,cols,spacing,radius, borderspace_l, borderspace_w, radius);
	# translate ([width/4,borderspace_l/3])circle(drill_via);
	# translate ([3*width/4,borderspace_l/3])circle(drill_via);
	# translate ([width/4,length-borderspace_l/3])circle(drill_via);

	# translate ([2*width/20,length/2-radius-spacing/2])circle(drill_via);
	# translate ([2*width/20,length/2+radius+spacing/2])circle(drill_via);
	# translate ([18*width/20,length/2])circle(drill_via);
}
}