Picture of USB to PS/2 convertor
Here i will show you a simple tutorial to convert your USB keyboard to comfortably adapt to a PS/2 connector in a computer.

The Situation
I had actually bought a flexible keyboard from the market and i had no idea that it had a USB socket to the output. I was using this USB keyboard for a couple of days and after using it for some time it was giving me trouble. Sometimes the keys did not function properly and sometimes it would automatically eject i.e disconnect from the computer port and again connect. I was having such problem and decided to find a solution for it.

The conception
After doing a bit of research i found out that most of the modern keyboards can be easily adapted to a PS/2 connector with ease. The only thing you need is just the USB socket and a PS/2 Jack (i got mine from an old mouse of mine). I also found out that when you buy a keyboard and if it is for the long run like in a Personal Computer, then it is better to have a PS/2 connector bought. Since the flaws for buying a USB keyboard are (i) It is gonna occupy one of the USB slots in your computer and hence there will be no space for USB when you are connecting multiple com ports. (ii)It is gonna use some kind of processor time since it has plugged into a USB. Very nice to have one more empty USB connector
Therefore my suggestion for you all if you are buying for a Personal Computer is to buy a PS/2 keyboard in place of USB. But again if you have already bought it then this instructables is gonna teach you how to accomplish the feat.
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Mr AbAk23 days ago
Nice Idea..
arupbsk3 years ago
This will not work.
The PS/2 keyboard is like I2C serial device. It has clock and data lines.
The hardware inside a PS/2 keyboard doesn't have capabilities to emulate a USB HID device as a USB keyboard.
Hence USB will give message device not recognized.
raikut (author)  arupbsk3 years ago
Well Mr. Basak!!
I think you have not read my instructables properly. I have already mentioned in my instructable that only some recent usb keyboard can be adapted for this method. And for your information i have already tested in my PC and it is working 100%. you can see the pictures in the instructables given.
And thanks for you comment

arupbsk is saying that a PS/2 to USB adapter won't work. He is correct.

You ralkut are arguing that he has not read your instructable properly, but you have in fact not read his comment properly and assume that he is saying that your instructable will not work. He is not. His comment is likely an answer to lukeD's question above.

lukeD, having tried it and researched it I can concur. It does NOT work.

arupbsk raikut3 years ago
Then it may be because of manufacturers making same COB IC for keyboards whether it is PS2 or USB.
Otherwise, theoretically it seems impossible because of different topologies in these two types of keyboards, which prevent them from interchanging interfaces (USB to PS2, or vice versa).

Anyway, thanks for writing a detailed instructable.
That is correct, and it has nothing to do with how recent the keyboard model is. Most USB keyboards are USB only, but some are USB+PS/2 compatible. It will say on the box if the USB keyboard will work with PS/2, and such keyboards usually come with a plug adapter that performs the same function as this DIY cable.
Certain keyboards have PS/2 support without having PS/2 output, just over these kinds of adapters
nixxx corp1 year ago
mgkbull1 year ago
Will this work the other way around? To get a PS/2 keyboard connected to USB? Thanks!
lukeD1 year ago
Can I make it the other way around (PS/2 to USB) with this method?
The information given here, also inadvertently states that if I wanted to Convert a USB to PS/2 Optical mouse that this information would be valid. The reason I ask is I have a Microsoft Comfort Optical mouse 3000. To which I have been using as a PS/2 mouse with the USB to PS/2 Adapter however recently the adapters (two) have stopped functioning. And Using the mouse as USB bothers me because it ejects it's self automatically after about 30 seconds and makes That sound when you eject a device, however once you move the mouse that irritating sound once again emits and begins functioning after a brief pause.
uamin2 years ago
can i use ps/2 cable to make an LED torch...?
raikut (author)  uamin2 years ago
Yes you can if you connect pin No. 4 and Pin No. 3 with a limiting resistor. You can make one. How many Leds you would like to light up by the way.
My suggestion is that if you use a single White LED, it would be fine. Just remember PIn No. 4 is positive supply and pin No. 3 is Negative.
uamin raikut2 years ago
i've plan to light up 5-6 LEDs, will it work on ps/2 cable..?
raikut (author)  uamin2 years ago
Just to know what color of LED would you like to light up. If it is white then the current consumption will be more and i doubt you will heat the system. My suggestion to you is that you try to light up not more than 2 white LED's.
And just asking you a question? For what purpose you need the torch for.
uamin raikut2 years ago
Yep, I want to use white color LED n I need the torch for my laptop. Now, as you told me that it would heat the system, then what would you say if USB cable is used and I think it might be worked...
raikut (author)  uamin2 years ago
well i am not talking about the wire will get heated up. But what i was telling that the computer system from where you will be powering up the circuit will get heated up, but if you insist you can click here, i have given the circuit diagram and you can connect it in this way
jbaker222 years ago
Hi i plan on transferring files to an old computer by usb, but it has none. Will it work to transfer files from an mp3 to a computer with this plug? Can this ruin an ipod if I try to sync it with this cable?
raikut (author)  jbaker222 years ago
That is just not possible, if you would like to transfer files from Mp3 to a computer. It man indeed ruin your Mp3. If you can give me a detailed description the i could help you on your matter
jbaker22 raikut2 years ago
Okay, then would you assume i could ruin a flash drive if I make the adapter have a female usb plug and plug it in?
raikut (author)  jbaker222 years ago
It may work if it routed directly with the processor. You can try but on your own risk
you have the same multimeter as me :)
raikut (author)  snowluck23453 years ago
That's great, think we are of the same brand. Are you onto ham radio
nodoubtman3 years ago
I have a ps/2 with wire, there's only 4 wire : red, brown, yellow and grew... how do i connect those to usb ?

thank you!
raikut (author)  nodoubtman3 years ago
That's correct PS/2 jacks have only 4 wires. The color don't matter. You first have to see the continuity of those wires with the jack.
Then simply follow the circuit diagram that i have given in the instructable. Many manufactures use different color of wires but you can check it with a simple multimeter and find out the pin outs where these wire lead to.
If you look at the diagram that i have posted you can easily connect the keyboard.
hello! do i have to test it out... one by one?

thank you!
raikut (author)  nodoubtman3 years ago
That's a Roger. You do indeed have to check the pins one by one and it will take hardly a minute to find out the connections of the wire in the jack.
And there are only 4 wires so it will definitely be an easy one.
Lorddrake3 years ago
going from a USB device to PS2 port is not a problem ... I use converts for this all the time at work.

It is when you try to go from a PS2 connection to a USB port. That requires a much more complicated converter in order to process the signal.

I don't know if I have anymore of the PS2 to USB converters, but if I can find one I will post pics so you can see the difference.
raikut (author)  Lorddrake3 years ago
That would be great if we had such instructables too.