Easy Stealth Footswitch / Pedal to Minimize Windows and Show Desktop





Introduction: Easy Stealth Footswitch / Pedal to Minimize Windows and Show Desktop

I spend most of the time at a computer programming, and in a matter of no time I end with all my screen real state filled with windows. Also, most of the time my feet are very lazy, so I took the idea I saw somewhere to do a very easy and cheap foot pedal to hide / unhide all the windows by using my feet.

Also, I had a lot of friends that would like to hide all the IM and youtube screens when the boss passes by, so maybe this will help =P

Most of the modern computer keyboards don't use the "Scrll Lock" (or Bloq Despl in spanish) for anything, so we will use this key to trigger the hiding function in windows.

I hope you have fun doing it as I had fun making it.

BTW, I was a member like for 4 years now, but this is my very first instructable.

Thank you!! and please have a look at my blog for extra pics: my blog

UPDATE: Just to be clear, this instructable is not about hacking your actual keyboard, but hacking and attaching an extra one to your regular computer, so you end using your regular keyboard and also this hacked one, both at the same time. Have fun!

Step 1: The Parts

1) An unused old keyboard - for the keys functionality (I had A LOT of unused keyboards at home)
2) A multimeter - not a must, but it really helps to check everything OK
3) An arcade switch - this will be the switch on the pedal
4) An unused cardboard box - I had several unused boxes from AMD processors, U can use one of these boxes
5) A soldering iron
6) A dremel tool
7) Some cable, about 6 ft.
8) The AutoHotKey free windows application that you can find here: http://www.autohotkey.com/download/

Step 2: Unscrewing the Keyboard and Finding the "Scroll Lock" Key

A keyboard works by closing a circuit between 2 plastic layers; when you press a key, the 2 layers get in contact and a current flow between this connection, sending a signal to the microcontroller inside the keyboard.

1) You will have to disassemble the keyboard. Remove all the screws you might find in the back, and release the back cover.

2) Then, remove the thin plastic layers thar are inside the keyboard.

3) then, put the cover on the back and turn the keyboard facing up, to put the layers over the keys to write with a permanent marker where the keys are, one for the upper layer, and one for the bottom layer.

Step 3: Finding Which Pins Works for Our Key

Then, you will have to find wich two pins on the microcontroller are the ones to be pressed together to close the circuit and send the key code to the computer, so:

1) Take the upper plastic layer (it's glued to the bottom layer, you can use a Xacto knife to cut the small glue spot that puts the 2 layers together.

2) Put one of the multimeter probes at the brown spot, and then put the other probe in the first of the circuit track endings

3) Get the resistance reading in the multimeter (the one with the OHM symbol on it) , if you don't get any reading, move the probe to the next pin in the track endings, until you got some reading.

If you don't have a multimeter don't worry, just follow the track until the ends, just don't get lost because of the tiny lines =P

Once you find where the key ends, do the same procedure for the bottom layer of the keyboard

Step 4: Soldering the Cables in the Keyboard Microcontroller

Ok, so now that we know which pins (or track endings) are the ones for our key, we have to solder some cable in the keyboard circuit.

Before soldering the cables, use the dremel tool to remove the black material over the tracks in the circuit, this will help the solder to stick to the circuit.

I will solder cables for the "Ctrl", "Alt", "Right arrow", "Left arrow" and "Scroll Lock" because I'm using this circuit for another project in the near future. But U just need to solder the cables for the scroll lock keys.

Step 5: Making the Foot Switch / Pedal

Then, you have to install the arcade switch in some kind of support. I used an old AMD processor cardboard box, very sturdy and lightweight.

1) Cut a hole in the box
2) Remove the black switch of the button and screw down the yellow casing
3) Tighten the yellow button with the plastic black nut
4) Solder cable to the ends of the switch
5) Attach the switch again to the arcade button and close the box

Step 6: Solder the Foot Switch to the Keyboard Microcontroller

Solder the two arcade switch cable endings to the soldered cables in the microcontroller, this way every time you press the button, the circuit will short, "pressing" the Scroll Lock key.

I used another old nokia cellphone box to keep the brains of the circuit to be used later in future projects.

Step 7: Programming the Scroll Lock Key to Hide All the Windows

So far, the foot switch only presses the scroll lock key, which is kind of useless. We need a freeware program called AutoHotKey to tell the computer to minimize all when we press the key. This program has a lot of functionality (sadly, only under windows and not in Linux), but we will use just the basics. If you want more information you can read the embedded help.


1) Download the program from http://www.autohotkey.com/download/ download the "Install AutoHotKey" option.

2) Install the program, it's pretty straightforward

3) Then we have to program the code in a text file called minimize.ahk , you can find the file for downlad below, but in case you want an explanation of the code, here you have:

SetScrollLockState, AlwaysOff ------------ this will turn off the scroll lock LED light

ScrollLock:: --------- if you press the Scroll Lock key, the function will minimize all the windows

+ScrollLock:: -------- if you pres the Scroll Lock key, while holding the Shift key, all the windows will return to the screen

You can download the file below, and save it inside the AutoHotkey folder in you computer.

Step 8: Load the File Automatically

Then, we have to load the file everytime windows starts, so you have to add a shortcut inside the "Startup" folder under the "Programs" tab at the "Start" button under Windows XP

Just drag the shortcut to the "Startup" submenu under "Programs"...

Step 9: The Video of the Pedal

I guess you can see the video here:


Step 10: Done!! Start Hiding Your Windows!!! =P

Then connect you fabulous pedal to your computer, I used a PS2 to USB adapter, so don't need to reboot anything.

Once you reboot (or load the script by right clicking in the AutoHotKey icon in the taskbar) you will be able to hide ALL the windows with just the press of a pedal!!!

And, if you press the pedal while holding the shift key, all the windows will be restored.

Well, this is a very quick computer MOD, you can use another kind of pedals, or a nicer box, but the idea is to kep it very simple.

This is my first instructable, so please let me know what you think about it!!!



P.S. I have a video with the pedal working, but I don't know how to upload the videos, any help?



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Love it!

And just mentioning the other project, I had to go check that one out too! I started working on this and got frustrated trying to find the two pins to close the gap for the keys I needed. I didn't think of using a multimeter rather than trial and error with a keyboard button test. It was a cool program though. It'll highlight the keys you press on an on-screen keyboard so you know if they are working. I don't remember its name but a google search will find it along with multitudinous others and might come in handy for someone reading this.

Now that you've shown me a better way to isolate the keys I need, I'm going to make a similar switch.


Hey thanks to you for your comment!

Good luck with you project, hope this instructable helps you. Let me know if you need something else.


Yeah, that's exactly what I got.
However, I made this work by simply replacing ''+ScrollLock with Pause. It works perfectly now, so I'm more than happy.

I'm currently running win 7, maybe this has something to do with it...

Hey! That file doesn't work, it only minimizes and doesn't undo :( Any ideas why?



mmm I'm not sure why it is not working, do you have this on the file?

SetScrollLockState, AlwaysOff

Just delete the dashes, keep the code and let me know

I've hacked Keyboards before, and usually use a Sharpie to trace the contacts, but this method of finding the correct pins saves a LOT of time and frustration. Thanks for the post! :)

would it not be better to have it trigger the computer to "lock" instead of minimizing windows?, or perhaps minimize the windows and then lock?

But I guess the idea is to look as if you were actually working =P a locked screen looks more suspicious hehe

thanks for comment!


Just a quick note that a Windows version of AutoHotKey is available (I currently have it installed in XP) - if anything, I think that you have gotten this wrong way around:

""This program is very powerful (sadly, only under linux) and has a lot of functionality, but we will use just the basics. If you want more information you can read the embedded help.""

That is in step 7 and to my knowledge, this is a Windows-only program that can be run under linux with WINE (it stands for Wine Is Not an Emulator) but due to the way that WINE works, AHK has only very limited 'power' - something to do with WINE acting similarly to a sandbox I think but I would advise that you look into that yourself if you're interested.

Anyhow, the point is that AutoHotKey is NOT linux-only.

Other that that minor correction and a couple of doubts re: bringing hardware into the workplace from home (that's not generally isn't commonplace.. is it?), its a Cool first Instructable =]

Keep up the good work!

-- Kwah

Awww, you're right!! I dunno why I put that comment about linux, actually autohotkey is only under Windows, my mistake. I will update that ASAP.

Didn't get ur last comment about bringing the hardware =P

Thanks for ur comment!