Talk:Replica 1

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Adding a -12v power supply for using an Apple II keyboard?

So my replica-1 works great. But I couldn't figure out why I couldn't get a keyboard response from the II+ keyboard (with encoder and adapter cable) that is part of the II+ style case I put together. Read the manual again, and noticed, "Please note, you will need to supply your own -12V power for Apple II keyboards."

I am interested to learn what solutions might exist for getting the II+ keyboard working.

FROM Henry: I believe, as you stated, it requires the -12v line to use an Apple II keyboard. I see you also posted the question here: http://www.jlaforums.com/viewtopic.php?t=461305056 Simplest I believe would be to use build a -12v circuit to make the voltage. Here are some examples: https://www.allaboutcircuits.com/projects/build-your-own-negative-voltage-generator/

I have 'cheated' in the past and used a +12v power supply which was isolated. Be sure you understand this concept of isolated. And then connect the positive line to COMMON on the board and connect the negative line to the -12v load. This USUALLY works, but don't quote me on it. And I never tried it on the Replica 1, so I can't guaranty it will work or not damage things.

Simplest I can think of could be to use a PSU that supplies all voltages and has a common between them all. The ReActiveMicro Universal PSU for example would work: https://www.reactivemicro.com/product/universal-psu-63-watt-switching-power-supply/ It does however add some bulk to the project compared to a simple USB AC power adapter. And you will need a cable to USB adapter too which will replace the USB power adapter and let you connect to the Replica 1.

Hope that helps.

Henry [END]

FROM Matt: Your suggestion gives me the idea of mounting a Universal PSU in the case, and hanging a dual-outlet system-saver (such as Kensington) off the side of the case. Both the PSU and the USB could simply plug into that. Seems a bit silly, but it might look kinda cool. I'm not sure I would know how to power the USB directly from the PSU anyway. Getting -12 to the keyboard will be challenging enough. Thanks for the great input!

Matt [END]