Samuel Demeulemeester has launched a crowdfunding campaign for the ATX2AT, an open source smart power converter designed to allow classic computing hardware based on the AT standard to be safely powered by a modern ATX power supply.
"The ATX2AT Smart Converter plugs on a standard 24-pin ATX PC power supply and acts as an intelligent protection device for old retro-hardware," Demeulemeester explains. "It can be seen as a couple of programmable fuses with monitoring capabilities. You can set the current limits and define how quickly it will react to an overpower condition. It was originally designed for vintage PCs (with AT-style power supply), but it can also work with old Macintosh as well as many other '70s/'80s/'90s computers, consoles, etc."
"The ATX2AT Smart Converter is dedicated to anyone who repairs or just want to protect their precious old hardware from disasters. It offers much more advanced and useful capacities than a standard passive adapter cable."
Those features include programmable over-current protection on the 5V and 12V rails, user-configurable reaction times for the integrated "virtual fuses" with fast- and slow-blow modes, an integrated converter to replace the -5V rail required by the AT standard but dropped in modern ATX supplies, resettable fuses for both the -5V and -12V rails, ripple filtering, and real-time current monitoring using an on-board 0.96" OLED display.
The design came about after Demeulemeester was testing a series of old motherboards using an off-the-shelf ATX to AT adapter. "I connected everything for the first run and flipped the switch on my ATX to AT adapter. After about 3-4 seconds, I heard a sinister crackling noise and immediately switched off everything," he recalls. "Too late: magic smoke came out from a tantalum cap.
"I removed everything and carefully checked the damage. The board was FUBAR: two caps almost totally destroyed and, much more serious issue, I had two burnt PCB traces on the back side. I would realize later that a voltage regulator was also destroyed in the process. Unfortunately, my 486 DX4-100 died. It seems the 3.45V regulator was bypassed and the CPU received 5V for some seconds. Both SIMMs survived, but I raged quite a bit and it was time to do something about that."
The crowdfunding campaign is now live on Kickstarter, with the adapter priced at €39 (around $43) plus shipping.