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Showing posts from April, 2009

FLL EV3 Robot

This blog post is about our current EV3 robot we're planning to use in the 2023/2024 FLL competition. Some features: 2 large motors for steering. 2 medium motors for attachments.  2 colour sensors for picking up the white and black lines, also used for line squaring. 1 gyro sensor. To enable attachments to be changed as quickly as possible we're using gravity to keep the gears connected, i.e. you don't need to fasten anything to the robot. Every attachment has 2x 12 tooth double bevel gear (part 32270) which comes in contact with the 2x 20 tooth double bevel gears (part 32269) on the robot. The medium motors are horizontally aligned on the robots, but we use 12 tooth double bevel gears to convert that to vertical alignments. These in turn are connected to 20 tooth double bevel gears, and the attachments in turn connect to these 20 tooth double bevel gears with their 12 tooth double bevel gears.  The complete robot is modelled in Bricklink Studio 2 . You can download the rob
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HP laptop power woes

My HP510 laptop had the strangest power problem: when running on AC power, the charge indicator LED plus the power button LED will suddenly start to blink. After this Windows will report that the laptop is running on battery power, and if left unattended the battery will eventually run out and the laptop will die - with the AC adapter plugged in. Even after I shut the laptop down, the LEDs keep to blink until I reboot the machine. Because the battery is old, I've removed the battery and all went well for some time. Then the laptop began to die whenever I touch the AC adapter, which lead me to the real problem: the wire coming out of the AC adapter was badly damaged at one spot where it was always flexed around the brick. I presume the blinking LED was some sort of indication that the AC adapter could not supply enough current for the laptop. So I cut the wire at that spot and soldered it back - and everything seems to be working again!
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A4 paper size

Let's start off with three basic rules: 1) The width:length ratio is constant for all paper sizes 2) Halving a paper along the long side will give you two transposed pages of the next smaller page size. 3) The area of a A0 page is 1m 2 We can calculate the width:length ratio as follows: Take a landcape A4 page, and dividing it in half will give you two portrait A5 pages. The width of the A5 page (w 5 ) will be the half of the length of the A4 page (l 4 ), and the length of the A5 paper (h 5 ) will be equal to the width of the A4 page w 4 ). Because the width:length ratio of both pages is the same, we can write: w 4 / l 4 = w 5 / l 5 w 4 / l 4 = l 4 / (2w 4 ) 2w 4 2 = l 4 2 l 4 = sqrt(2) x w 4 Using the result above, the width:lenght ratio can be written as: w 4 / l 4 = 1 / sqrt(2) The area of an A0 page is 1m 2 , A1 is 0.5m 2 , etc. The area of a An page can therefore be written as 1/2 n m 2 . Because the area is the product of the height and length of the page, we get t
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