Does anyone know how much current can be safely drawn from the +12V supply at the keyboard connector? The Apple-1 manual is clear about the availability of 1.5A on the +5V supply and, clearly, this is the preferred source for powering external devices. But I do need 12V. I could, of course, use a boost converter to step-up the 5V to 12V but that does seem overkill when 12V is available in any event.
My understanding is that the LM340-12 is rated at 1A. However, T2, which is itself only rated at 1A, is required to supply the -12V and -5V lines as well. Accordingly, the +12V line seems to be rated at 500mA. As far as I can tell, the +12V is only used for the RAM chips. Each MK4096 draws about 1.5mA on standby. So if all 16 sockets are populated, that would be a total of 24mA - leaving 476mA available - more than enough for my purposes. However, when active, the RAM chips can draw as much as 30mA. If all of them were active, this would be a total of 480mA, leaving only 20mA which is far from sufficient for my purposes. However, I would have thought (but this is pure guesswork on my part) that only one chip would be active at any one time, so that the current draw from the RAM would likely be 15 x 1.5mA + 1 x 30mA = 52.5mA, again leaving more than enough for my purposes.
I suspect I need a minimum of 170mA from the 12V line. Ideally I would prefer to comfortably have over 200mA available. Do you think I will be able to do this with the +12V supply?