I cannot seem to find my camera, but i have built a walking robot [well, it has front  legs and back wheels, but the legs are what make it go forward, or backwards. It works OK, but i’m sure with a better leg design it would walk more efficiently.

This robot is kinda inefficient, as it takes 2 steps forward and one step back. But it still travels, works better on solid smooth surfaces than, say a rug. It works really well on my mouse pad, which is soft foam with a layer of cloth on top, all a solid piece.  The robot is actually very simple and most of it can be made just by looking at a side view since all the mechanics are on the outside for looks.

It does walk very slowly though, maybe an inch every 3-5 seconds, depending upon the surface.

Pictures to follow if I can find my camera. I took apart the solar panel idea. It worked, but I found that the solar panel charged the battery the first day, and it didn’t really need charging for the next week with the LED output of only 4 led’s…

Program for the solar panel hookup to the NXT and a full schematic will be around soon…


Preview for Solar Battery Backup Device using Lego Power Functions

There will be photos and video of the project coming soon, but I can tell what I have so far.

I’m taking a shoe-box and converting it into a battery backup. Although I’m only using a power functions battery box filled with 6 rechargeable 2400mAh batteries, creating a total of 7.2v and 14400mAh, it’s only powering LED’s, which use about [according to my research] 10-20mAh. That would amount to [with 20mAh] about 720 hours of light in one charge, with one LED. If I ran LED’s for 8 hours [overnight], then I could run at least 30 LED’s. That would be plenty of light for a room or two… and during the day I could charge them with the solar panel, and use a small power regulator, maybe the NXT, but could be as simple as running a motor while charging in the sun to keep the rechargeable batteries from overcharging. I could run the NXT all night easily on a rechargeable battery pack that I bought for it from Lego Education [a site full of bulk Lego’s!], but I could only trust the power pack and a wall socket with the best power-strip with all sorts of protection for that.

The great thing about Power Functions is the plug. It has 4 wires, as follows:

positive [0v]

variable [the direction of the swich on the battery box or the separate switch uses this to run the motors and lights]

variable [reverse charge of the one directly above for return voltage]

negative [full battery charge, for me, its 7.2v]

Using the two outer ones, I can charge the battery without impairing the ability to run the motor in either direction. This is really useful, although I don’t like the design for the external switch because it doesn’t work independently of the battery pack to send a voltage to the motor or led’s – only the battery pack can use the outer wires, and the motor and switch can only use the inner ones [but the switch, regardless of position, will always send voltage through it on the outer wires. I assume this was used for the Infrared receiver and other parts to work with it, independent of the position of the switches. The good thing is that when you switch the battery pack to the off position, it shuts off all the wires, including the outer wires. This in some places may not be extremely useful, but the use is good here because I can control it better from the external switch anyways… If you really didn’t like it, I’m sure it’s not too hard to take apart the battery box and edit that problem, but I like it in it’s “vanilla” [original] form.

I hope to have pictures out soon, maybe a video too.

power functions port wiring by jared