Hall Effect Device switching a logic circuit.

In picture One above the LED a HLMP-1600 is on. In picture Two above it is off.

The logic device is an SN7437N, a Quad NAND gate based buffer. The Hall Effect device a switch is a rather old RS276-1646. The ancestory of this device is that of the original Sprauge UGN-3120T. Then it became a Allegro UGN-3120T, now it is a Sanken/Allegro UGN-3120T. But the device is still a Sprauge UGN-3120T. It is about thirty years of age. The SN7437N is much younger, say about two years of age. TI switched into maintenance mode for all TTL logic circuits during the 1990s and originally wanted to close the line. But reason prevailed and they decided to continue making only parts still in need.

The original device is from the Eighties. But I believe it goes back even further then that as it is listed in a book on TTL logic from the Seventies. Perhaps it might even date back to the beginning of the original product line.

As for the circuit displayed, it is a common one used to demonstrate such activities, and is even found in an applications note on the subject by the manufacturer.