Introduction: Control Electrical Stuff With Your Computer

Picture of Control Electrical Stuff With Your Computer

Control lights (or any thing electrical appliance) with your keyboards lights. with no irritating micro controller!!!!

First I want to say that this is my first instructable and I didn't take many photos.
also I got the idea from: USB controlled mini lava lamps by jamesh

this is a device that turns lights (or what ever) on with the push of the caps num or scroll lock
if you want you can use an xbox DVD remote with your computer and turn on your lights with that. so you can walk in to the room and push a button on the remote and the lights turn on

Waning. this instructable involves working with high voltage mains power, I take no responsibility if things go wrong.

Step 1: Get the Parts

Picture of Get the Parts


3 transistor BD140
3 capacitors 10-60uf
3 resistors (so the LEDs don't burn out. unfortunately I forgot there value)
3 relays (the ones with 5 legs)
3 switches (single pole double throw) 240v (120 in the US)
1 (single pole single throw) switch 240v (120 in the US)
a box
4 grommets
A keyboard with num caps and scroll lock lights
3 LEDs
7 (or more) meter extension lead
2 power sockets (see picture)

xbox dvd remote
USB cable
small blank circuit board

Step 2: Opening (and Modding) the Keyboard

Picture of Opening (and Modding) the Keyboard

Crack open your keyboard and remove the circuit board (mine had a zillion screws holding it in)
then locate the lights and solder the wires to the legs of the LEDs (see picture)

when done put the keyboard back together. you may need to cut a hole for the new wire to get out

important note: not all keyboards work with this

Step 3: Prepare the Cord and Box

Picture of Prepare the Cord and Box

cut the extension lead into 4 equal parts
drill 4 holes into the side of the box
shove the grommets in to the holes
tread the cords trough the grommets (spit helps)
strip the wires (the end thats in the box)

Step 4: Put the Socets On

Picture of Put the Socets On

the extension lead should now be cut into 4 pieces and treaded trough the box

now its time to put the sockets on the cords that don't have any.

the sockets should have instructions on how to wire them

Step 5: Electronic Bits

Picture of Electronic Bits

now this is the most fiddley bit, putting the circuitry together.

I was too lazy to make a PCB so i soldered wires to the components

Step 6: Put Every Thing in the Box

Picture of Put Every Thing in the Box

you need to cut some holes for the switches, wires and lights

make sure all the wires in the box a insulated

Step 7: Plug It In

Once you have put every thing in the box and it looks like the picture above than you can now start to test it.
plug a lamp (or something) into one of the sockets and plug the keyboard into the computer
then plug the power in and turn on your computer if nothing explodes, good.

now the lamp should flash as the computer boot (this is normal)
when the computer is done push the caps num and scroll lock buttons, an led should light up for each button.

if it doesn't than open it (unplug it first) and check all connections.
if all the lights turn on when you only press one button, than check the connections if that doesn't help than it may be the keyboard, not all keyboards work with this

Step 8: Optinal Stuff

Picture of Optinal Stuff

if you want you can use your xbox DVD remote, you will need a USB cable and a piece of circuit board and etch it (theres lots of instructables on how to do this) , then cut so it fits into the plug on the DVD remote sensor

its hard to explain so just look at the pics

Step 9: Software for the DVD Remote

Picture of Software for the DVD Remote

you need software to run the xbox DVD remote:


once you have installed the software, plug the sensor into the USB port, it should say it found new hardware. if it says "USB device not recognizing" than try moving the connection.

once the hardware is installed run XBCDRC (should be in start menu)

then choose what buttons control num caps and scrol locks

(this picture was taken on an XP computer)

Step 10: How to Use It

if every thing works than you have completed it successfully

the switches on the front are wired in a double switch so you can manually turn on or off the lights

the single pole single throw switch is to disable the lights.


MartinC31 (author)2015-08-27

The USB keyboard gives 5v, and standard relays needs 6v, im using a bc558 transistor but it doesn´t haves enought power to switch the relay. any idea?


zilani (author)2010-08-24

can any one plzzz tell me the value of resistance?

cring (author)zilani2011-11-09

Okay the answer to your question is not a simple one but here goes. The resistor is to prevent too much power going through the LED.
Therefore, the value of the resistance is dependent on the wattage of your LED.
Example - 1/4W LED. 5V - 330ohms 9V - 680ohms 12V - 1kohm 24V - 2k2ohm
Look up Ohm's Law on Google if your voltage/wattage combination isn't listed.

shivangi_nig (author)2010-02-08

m realy new n fresh in des works . . .bt hopin fr d best . . .takin dis project as my first work . . .really hv no clue abt hw to go on . . .so plz leave ur comments fr help . . .peace . . .

translated version: I'm really new and fresh in this sort of work, but i am hoping for the best as i take this on as my first project.I have no idea how to start, if anyone would be kind enough to lend a hand, please leave a comment, your help will be greatly appreciated.

K-NiigT (author)shivangi_nig2010-05-15

I cnt udrstnd ur tpng cuz its msing 2 mny lters.

Redgerr (author)K-NiigT2010-07-08

you left the "E" in in "lters", taking out the vouls only works if you do it right K-NiigT (i like the monty python reference) ;) and yeah shivangi_nig, your not making sense, sorry...

fcassia (author)2008-12-01

What happens if you plug two keyboards? I mean, are two keyboards individually addressable on Linux? Can you keep keyboard#1 configured and working "normally" and then connect a "secondary" USB keyboard for this purpose?

srilyk (author)fcassia2009-12-07

 Well, the builtin keyboard on my lenovo x61 tablet doesn't turn on the caps light when I plug in my usb keyboard and hit caps, so I think you could. This instructable shows you how you could eliminate a lot more space.


qsiguy (author)2009-10-13

Another option for activating the caps lock, num lock, etc. if you are using a windows machine is to click start -> run -> then enter "osk" (without the quotations).  This opens an On Screen Keyboard where you can just use the mouse to click on the buttons you want.  This will activate the num lock, caps lock, etc. LED's without using the actual keyboard and turn on your remote accessories.  FYI..

prodlad (author)2009-09-15

Whats wrong with a relay?

therian (author)2007-11-14

religion forbid to use serial port ?

maffiou (author)therian2007-11-16

Well, I don't think you can get more basic than this... If you want to use the serial port, even if it's just the control line, not the data (which would probably require a microcontroller) you'd need significant programming on the PC side... I personnally used a parrallel port in the old day, It worked fine... But these days, not every computer has one... Shame really, that was quite diy friendly...

relay (author)maffiou2009-05-05

true, i did this as a novelty and to show other ways of computer control, the computer i use during that also has a controller on its LPT port which i use for controlling pool pumps (i should probs wright an article about that, seeing as i made a heap of custom network control software for it) but really i use the LPT for serious stuff and this one for things like desk lamps id also like the parallel port stay for this sorta stuff. thankfully alot of motherboards still come with them if anyone would like too see some of my c++ apps for parallel port control, do ask, id be happy to post it for others

balmacjo (author)2008-02-14

This is way cool!!!

By the way, can you do this without using a keyboard?

I mean just controlling the power switch turn them on and off just using programs on the PC. No manual intervention needed... Via USB connection...

Originally I plan to connect it to a main switch but dont know if it can be possible for very hign voltage...

turbonegro (author)2007-11-11

what about using solid state relays instead
easier methinks

relay (author)turbonegro2007-11-11

I used mechanical relays for 2 reasons 1 I had some at the time 2. the mecanical ones have the normally open and normally closed, so theres a double switch. so you can manual turn the lights on or off, and the computer can do the same

wi-fi astronomer (author)relay2007-11-18

When you use an old fashioned relay, you need a transistor first. Way easier to use a solid state relay that takes a control voltage of 5 volts. They also have the desired isolation of the house current from the printer fitting. See my comments above!

relay (author)wi-fi astronomer2007-11-20

but it doesn't use a printer fitting, Iv got another controller for the printer plug but I think i Brock it (I put the power in the wrong way) the point of this instructable is to demonstrate that you don't have to use the printer port, and that one can use a USB keyboard. also i said above that the mechanical relays have a normally open and normally closed. hears a little GIF explaining the need for mechanical relays.

Patented (author)relay2008-01-30

how did u make the draw?wich program?

relay (author)Patented2008-02-07

I made the GIF with Beneton Movie GIF 1.1.1Beneton Movie GIF 1.1.1 (I think)

Patented (author)relay2008-02-07

Nice!thank you!

Dr_Acula (author)relay2007-11-12

My personal preference is also mechanical relays. I went off solid state relays after discovering they leak very slightly when off - especially when driving flouro lights. When I turn something off I want it to be really off, especially if it is mains voltage!

Yes, solid state relays have that problem. This means that if you control a fluorescent light with one, it will flicker dimly when it's supposed to be OFF. If you use them, you design accordingly. If you want the device to be really OFF then you want the electromechanical type relay. I prefer the solid state type because of how it makes wiring up the system easier and design around the "never completely off" problem. It's a tradeoff. And of course tradeoffs are always found in engineering. Note that the same problem of solid state relays are found with triacs too. That was how I first found that problem.

jab0592 (author)turbonegro2007-11-11

Hello kwl build but are u english or american? if american how can u make it work for engalnd?

maffiou (author)jab05922007-11-16

I don't think it would make any difference, the high voltage side of thing can handle whatever the relay can handle... 110 or 240 doesn't make a difference... It's more the amount of power that play a role, and this is the same regardless of which side of the pond you are...

jongscx (author)jab05922007-11-12

I guess you would just need to make sure that the relays you use can handle the Wall currents there... it's 220V, right? Never been, so I'm not sure...

modest_mouse_fan (author)2007-11-23

very cool! i will definitely do this! Thank you and oh by the way, instead of just hitting caps lock, num lock, scroll lock, etc, im going to make a VB interface so i can do it with my mouse :D

arevolutionist (author)2007-11-15

Ah! I did the same project as you and was recently going to post it. =]
My design is different though.

thinker (author)arevolutionist2007-11-22

you can still post it
different ways to the same end is what instructables is all about !!!

myrhymeandreason (author)2007-11-18

Were you in a cave when you took these pictures? Really dark.

wi-fi astronomer (author)2007-11-17

I've been doing something like this since Year 1992. The best way to do it is to use some solid state relays (like the Halloween controller) and use the printer fitting with DOS or Win95 or good ol' Linux. For present-day Windows, you need SOME way to use the serial fitting or a USB fitting with a USB to serial thing. QBASIC will work with serial fittings 1 to 4. For fully computer-free operation try this: Get a solid-state relay that 5 volts DC for the control electricity. Next, get an audio transformer from a Radio Shack and hook it to said relay with the high impedance side to the relay. Next, hook the 8 ohm side with a volume knob in series to a stereo and the controlled side to 120VAC and Christmas lights. Make sure the lights will flash on their own first and set them up as desired. The last step is Use It! Fire up the stereo and adjust the knob so the lights flash to the music AND on their own as well. Using a triac (and burning up equipment) I pioneered this in 1984! Solid state relays are great as they contain a good triac. You can get 16 of them to work separately on one printer fitting by the 4 by 4 matrix methof. That is, if your software goes fast enough to way outdo 120HZ. Given that a triac stays on until voltage goes to zero, if the controlling computer is way faster than 120HZ (pretty easy!) you need no small caps across the TTL-compliant control side of the things. Think of the trick of multiple 7-segment LED number displays. Have fun! (author)2007-11-16

Seriously, a little spell check would go a long way in this thread AND comments! Nice instructable though.

Qtronik (author)2007-11-16

On my wireless keyboard, I take the receiver plugged on my usb computer... for those who thinks they can't do it bcz they do not have cord keyboard.

homunkoloss (author)2007-11-16

I used a K8055 Velleman kit for the connection to the computer an relays to switch my lights. mfg Daniel (who speaks normally German thats why he has such a bad english) ;-)

Stephen_A (author)2007-11-15

You should mention that there is another alternative to etching your own board for this - which is carefully popping the top off of the receiver and wiring based on Redcl0ud's schematics... Which may be more practically for most people.

NRen2k5 (author)Stephen_A2007-11-16

Or how about using a breadboard? Then you cut down on the amount of soldering you have to do, too.

TechnoMancer (author)2007-11-15

that wire that you say does nothing is probably the cable shield braid. it is an earthed shield to prevent interference from EM radiation.

Theodor (author)TechnoMancer2007-11-15

Nope, I believe you're wrong. Think it's called video sync, or something. All Xbox controller connectors have a fifth pin (the yellow cable) that is intended for gun controllers (for shooting games, for instance duck hunt (Yes, I know, never available for Xbox)). The shield is connected to the shielding on the connector. Besides from the fifth pin, xbox connectors use USB protocol.

TechnoMancer (author)Theodor2007-11-16

sorry i didnt read what you were doing i assumed it was a usb cable. lol. yeah the video sync is so that you can use stuff like guns but they only work for CRTs unless you may be able to simulate the scanning on an LCD by turning one pixel off and then continuing down the screen turning the next pixel black then back to what it was ment to be.

moreice (author)2007-11-12

you could use an optical sensor to check if the light is on --- saves u from taking apart keyboard

jongscx (author)2007-11-11

Wait... so basically, this will only work for a computer that you're not actively using, as accidentally hitting one of the lock keys while typing might turn your lights (or blender, as the case may be) on or off... So I guess only use it for a computer being remotely controlled. Another thing to be careful of, is the relay that you choose. Make sure 1) it can handle the current you're trying to switch, and 2) the computer can handle the current needed to drive the coil to switch it. In any case, very nice hack. I've personally never thought about using those status lights before, but it's definitely ingenious.

JonDarkwood (author)jongscx2007-11-12

Provided you can use any key to control this, you could easily set up combinations of hotkeys using the program AutoHotKey. I currently use AutoHotKey to set F1 through F4 as remote desktops and FTP servers I constantly need access to, and to turn my Caps Lock key into a command prompt key.

XCabooseO (author)2007-11-11

I'm gonna make one of these... definitely, I'm also gonna reprint on the keys so I know what means what. OOOOOOOOOHHH!!! Just thought of mounting it...

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