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Testing the machine and the solution

A project log for Modern Replacement Power Supply for a TI-99/4A

I bought an estate sale TI-99/4A, but it was missing the external power brick. What now?

kjohKJoh 6 hours ago0 Comments

Would this computer even boot?

Taking what others had done before me, I went with a series of modular buck converters to derive the +12v, +5v and -5v supplies expected by the machine.

I installed them on a small protoboard, jumpered into the TI's power header, and sure enough, I had a working machine.  Yay!

The datasheets for these devices specify ceramics, but I went with electrolytics for some reason.  I guess I'm used to working with linear regulators which usually get electrolytics on the inputs and outputs.

Below is the schematic:

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