Powering an old IBM PC Keyboard
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Powering an old IBM PC Keyboard

by anormal on Fri Apr 06, 2012 1:17 pm

i am new, looking here and there and have a question,
i've read the FAQs, search the forum, etc... Also i haven't touched a soldering iron since a pair of years...
so please deal with my Qs if sound too stupid for you :)

i want to connect my old and dearest old ibm clicky spanish keyboard (aka Model M, aka the best keyboard ever made) to my ipad 2

as some of you could know, you can connect a usb (or ps/2 with converter to usb) keyboard (and mouse) to the ipad and use it, all you need is a camera connection kit
also not all keyboards works, the connector of the ipad is capped to 10-20mA since iOs 4.2 (i've read this in the web, and i am unable to confirm this)

yes i could use (and i already have some of them) a bluetooth keyboard, but if you are thinking about this solution, then you obviously haven't used a clicky in your life :D

so i can power the keyboard with a usb hub connected to a PC, but if i want this solution portable, i thought powering it with batteries... until i found mintyBoost

This is the idea:

[ipad] <--- camera connection kit <--- ps2/usb converter <--- old clicky keyboard< --- +5V/500ma from Mintyboost

what i want to know if this idea is reliable, could MintyBoost be used to power a keyboard, instead of use it for charging devices?

i've searched the entire web and found this information about the keyboard, maybe this information is useful for you:

"Another relevant factor is that the older technology used on the IBM keyboard's controller PCB requires more power to operate than newer keyboards. The IBM draws around 112mA from the interface, whilst a modern keyboard draws 1.2mA. These figures are with the 3 status LEDs (NumLock, CapsLock, ScrollLock) off. Each of these draw around 12mA when lit on both keyboards.

The problem was cured by installing two 4.7k pull-up resistors (1/4 W, 5%); one each on the Clock and Data lines. The resistors were installed directly onto the keyboard's controller PCB. The modification was easier than expected as there were three convenient 'vias' (plated holes through the board) which were on the correct signal traces and could be used to mount the resistors."

thanks for your time!!!
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Joined: Fri Apr 06, 2012 12:52 pm

Please be positive and constructive with your questions and comments.