The NL301 Pulse Generator is a low cost module for producing trains of uniform TTL pulses. It can be operated continuously, switched off, or a single pulse can be triggered manually. A “gate” input socket is provided to allow synchronous trains of pulses to be gated-on by an externally applied TTL signal. Pulse frequency is continuously variable over more than three decades and three fixed output pulse widths are available. The frequency range and pulse widths were chosen to make this module suitable as a timing source for electrical stimulation of the nervous system, without the necessity of additional modules for determining the pulse width. The NL301 is also useful for a variety of other timing purposes where a widely variable rate is desirable, and precision is important but not critical.