DIY Linear actuator out of scanner parts and a drawer slider

To build this linear actuator I stripped off from a scanner the motor + gears along with the timing belt and the pulley. I bought in Brico a cheap drawer slider and screwed it all into a piece of wood.

First the video showing off what all this is about

Below you can find a pic of one end of the actuator:

As you can see, I attached the stepper to the piece of wood by just using a wire, and it works great!
Also note that zigzag piece of metal that links the timing belt with the drawer rail. In the picture below you can see it in more detail

The timing belt is sandwiched between two pieces of metal.

And finally below you can see the pulley at the other end, this was a tricky part, keep reading more the details!

This pulley had an axis that was riveted to the chassis of the scanner, I pulled it off with my pliers and welded it into a screw using solder, I had to heat both parts for a long time before in order to get the solder to bind both parts, the picture below shows the results:

And voila, its working better than I expected! Keep tuned for more and thanks for reading!

BTW greetings goes to the guys in timelab for inspiring me!

A Pre Amp for an electric guitar

I bought an electric guitar and needed an amp, I thought is was kind of silly to buy one since I could use my computer speakers. You cannot connect the guitar to the computer amp directly since the signal coming from the guitar is too weak, you need a preamp.

I had a bunch of 741 op amps around and decided to build a preamp myself. I used a inverter amp configuration (quite a simple one) and it worked great. By cranking up the gain by a lot I get a nice heavymetal distortion.




Here is the schematic along with a link to see it running in a free java circuit simulator.

Click here to see it running in a Circuit Simulator (needs Java)

The only problem is that the preamp seems to amplify too an FM radiostation and I can hear some nice music while I play guitar....

At the beginning I thought my guitar was haunted by The Beatles and played on its own, when I hard a kind of a voice I suspected it could be receiving some sort of radio signal.. 

 You don't believe me? Check out this video! 

Gameboy Cart Using an AVR

Built a Game Boy flash cart using an AVR. Took a cartridge I bought for a few euros and replaced the ROM chip with a 32Kb RAM I took from a printer. The pinout of most RAM, ROM and EEPROM chips are almost the same, I was quite glad about this :-)

The next step was to find a processor that had many free pins to drive the 15 for the address bus and 8 for the data bus, for that then I used and AVR128.



If you look at the cartridge 'pins', you'll see a cable soldered to one of them, that is the HALT line of the Z80, controlling this pin I can freeze the Z80, this way the data and addresses buses are free and my AVR can write and read data from my RAM.



This is how the whole setup looks like once connected, the big chip is the AVR .

I can write programs in the RAM in two ways:

1) Connecting the AVR to my computer through a serial port and use a little loader to upload apps.
2) Write the app I want to upload in the AVR's flash and have it write it to the RAM when the Game Boy is turned on.

So, bottomline :-) It worked for small apps < 16Kb but it didn't work for bigger apps, so I think this post will have a second part someday, stay tuned!

How to get support for the Arduino oscilloscope (and Parallax),

We now have a forum, please ask your questions there!

http://groups.google.com/group/xoscillo

Thanks!

Arduino oscilloscope (and Parallax)

I wrote some software so you can use your computer as an oscilloscope.

In the following screen shot you can see the software acquiring data from an arduino and also from a Parallax USB oscilloscope simultaneously.




For more info, more screen shots and source code go to:

https://code.google.com/p/xoscillo/

We have a wiki with the instructions and a forum, please use them! ;-)

DIY Laser projector

So yes! Hello!!! This time I built a laser projector, it was built using a toy laser pointer, a pillbox, a cooler fan and an arduino microcontroller.



Check out this video if you want to see it in motion (note that its a bit dark, but towards the end I turn on the lights)

Here is how it works!

In the picture below you can see the whole setup, the heptagon is a pillbox, its sitting on top of a cooling fan so it spins very quickly. Each side of the pillbox has a mirror that reflects the laser beam onto the screen.



Because the mirrors are moving the reflected laser dot sweeps the screen from left to right, because it does it very quickly your eyes actually see an horizontal solid line, in this case you see 7 lines one on top of the other because the each mirror is at an angle.

So I would get something like this:

-------------------------------------------------
-------------------------------------------------
-------------------------------------------------
-------------------------------------------------
-------------------------------------------------
-------------------------------------------------
-------------------------------------------------

if I turn off the laser at the right time, I could get to display something like this

--    -- -------- --      --         -----     --
--    -- --       --      --        --    --   --
--    -- --       --      --        --    --   --
-------- -------- --      --        --    --   --
--    -- --       --      --        --    --   --
--    -- --       --      --        --    --
--    -- -------- ------- --------   -----     --

Then with a little bit of software magic you can get the text to scroll, wave, and so on.

We are not there yet!

The spinning speed of the fan is very critical, any slowdown will cause the image to wobble, that is why I put this fins on the pillbox, when they spin they pass thought an optical sensor (pretty much like the one elevators have to keep its doors open when people leave or enter the elevator) A micro controller can use this data to compute the fan speed and adjust the laser blinking to the image looks correct.

Tricky part! (warning quite geeky stuff coming up!)

So how does the micro controller know when is the first mirror coming? The fins, because I glued them myself by hand, are not really equally spaced, some are closer that the others, the micro controller notices this and uses this info to tell which one is the first mirror... for example the two fins before the first mirror are a bit closer than the others.

That's all, I hope you enjoyed!


Other Laser projectors:

http://heim.ifi.uio.no/haakoh/avr/

poor's man CNC hot wire cutter - Updated!

This time I built a computer controlled device that will allow you to cut out shapes from styrofoam boards with great precision.

To make it more fun I tried to build the whole thing by re-purposing scrap parts I found here and there, so I used a couple of scanners, a hanger and a hot wire. The scanners I found them on the trash (officially I will deny that I pick stuff from the trash), the hanger I got it from my cleaning service and the hot wire was 3 euros.

This is the way it works, draw a shape using your favourite drawing software or download one from the internet, just make sure the file is a SVG, because that is what my system understands.

I found myself this nice eagle, which is quite a complex shape as you can see:
And this what you get:



Here is the promised video so you can see the system in action...




Here are some pictures showing details of the CNC