Magnetic core memory sense amplifier

Schematic / Breadboard

     The 1752 is a 4 channel bipolar magnetic core memory sense amplifier where the sense threshold for all channels is programmable with a single resistor. When core transitions are detected their signal is latched and may be read from the tristate output buffers. A control input allows the latches to be cleared prior to driving the core current lines.

     The outputs of the sense comparator OR gates are coupled to the latch clocks via low pass filters with a 350kHz cut off frequency to aid in suppressing false triggers due to rising and falling edge transformer coupling into the sense line. For increased noise immunity, external 1000pF capacitors are recommended at each of the 4 sense inputs.

     When combined with a 1747(C) core matrix and four 1749 H-Bridge drivers a 64bit memory is realized where each core is individually addressable via an 8 bit data bus and 8 control lines.

Specs:

• Input power: 3.5 to 5.5VDC
• Logic power: Same as input
• Threshold range: +/-0 to +/-165mV (Circuit limited, RSet grounded)
• Threshold range: +/-0 to +/-100mV (Practical)
• Threshold calc: Vthresh = +/-(10 x (0.95V/RSet))
• Comparator to latch filter: 350kHz -3db cutoff