The dynamic design of a tunnel-diode-transistor combined circuit and the applied pulse circuits are discussed. The combined circuit, in which a tunnel diode is connected in parallel with the collector junction of a transistor, is used. The dynamic design procedure is considerably simplified by describing the transient behavior of a tunnel diode with a set of approximate expressions and by the help of a selfanalog simulator. This circuit is capable of carrying out both memory and majority logic operations, and serves as a basic unit for several different pulse circuits, such as a mcnostable circuit, a frequency divider, a ring counter, etc.