11 Mar
2015
11 Mar
'15
1:22 p.m.
On 2015-Mar-10, at 8:08 AM, Vincent Slyngstad wrote:
I've got a technical question about core memories.
I've been looking, in particular, at the MC1540G sense amplifier. There's an
external capacitor that is supposed to be connected between pins 1 and 10 (it looks like
about .01uF was traditional). Maybe I'm being thick this week, but I don't quite
get what this does for the circuit. It's part of the "DC restoration"
section.
I think I have some idea what amplification and slicing mean in this context, but
"DC restoration" isn't firing any neurons.
Can any of you that have studied how core works help me understand this?
Looking at the 1540 internals schematic, it looks like a frequency compensation
capacitor.
Early op amps like the 709 required external capacitors for freq. comp.
Core sense amps are essentially a form of voltage comparator adapted to respond to the
absolute value of a differential input (produce the same output for a voltage difference
of either polarity at the inputs), and voltage comparators in turn are essentially op-amps
running open-loop.
(if that helps any . . )