A series type d.c. negative resistance for analogue computers

Negative resistances are only conditionally stable, the shunt type when connected to a positive resistance of a smaller value and the series type when the load resistance is larger. Hence, in general, in an electrical resistance analogue, both series and shunt types of negative resistance will be required. Methods of obtaining these two types of negative resistance for operation at both d.c. and a.c. are described. The principle, design and operating limits of the series type of circuit are discussed in detail.