The ATnoX was born out of the necessity for me to have a small adapter adapter I could use to fit AT/XT motherboards into modern cases, powering them with ATX power supplies and turning them on with a momentary switch (the standard power on button present in computer cases built in the last 20+ years).
The ATX2AT is a wonderful device (I own several of them), but I prefer to use it to test my boards and then fall back onto a cheaper alternative I can close inside a case without it feeling like a waste.
In fact, the output connector uses the same pinout as the ATX2AT, but as I still had a free pin available, I decided to include a TICK generator: a 50/60hz square wave signal required by some big-box Amigas to turn on.
14 pin connector, front view.
____
.----.----.----|----|----.----.----.
| 14 | 13 | 12 | 11 | 10 | 9 | 8 |
|----+----+----+----+----+----+----|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 |
'----'----'----'----'----'----'----'
- +12V
- +5V
- +5V
- GND
- GND
- TICK (50/60Hz depending on X1)
- -5V
- +12V
- +5V
- +5V
- GND
- GND
- Power OK signal
- -12V
TODO
- -5v onboard generation via a 7905 regulator
- Momentary button power-on support
- Header for power led in case the motherboard lacks it
- Power on button included on board for bench testing
- Optional amiga Tick generator
- 4 Layer board (middle layers are +5v and GND)
- logic-4000 libraries taken from alexisvl/kicad-schlib
- ATX power-on circuit taken from skiselev/isa8_backplane
- Amiga Tick generator taken from Aminet
- Thanks to @A-Small-Mice for the printable case