These modules provide the basic pulse generation mechanism within a NeuroLog System.When appropriately used, the NL301 Pulse Generator and NL304 Period Generator can initiate repetitive pulses/periods which can be used to synchronize external devices or form the basis of more complex stimulation protocols.The NL412 is a simple handheld trigger box which can be used to start or gate a protocol and is also used as a remote “buzz box”, useful when making intracellular recordings with the NL102G DC Preamplifier.

NL301 – Pulse Generator

The NL301 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.

NL304 – Period Generator

The NL304 contains a crystal oscillator and frequency dividers for producing a precise, stable frequency standard. It can be externally gated (GATE IN) and synchronised with an external source (RESET input). The pulse train can be switched off and a single output pulse can be produced manually by a front panel push switch.

The NL304 is the basic “clock” of the NeuroLog System as it provides the “fine grain” (1 microsecond increments) necessary for digital control of pulse width, cycle duration, delay, etc using the NL603 counters.

NL412 – Pulse

The NL412 is a small, handheld, general purpose pulse generator which can be used to “start” experiments, command the “gate” of a train of pulses or be used with an NL102G DC Preamplifier to “Buzz” electrodes.The NL412 is self-powered by a standard internal 9 V battery and is fitted with a 2 m lead terminating in the standard Lemo connector. It is now supplied with all new NL102G amplifiers.

Start – On pressing the button the NL412 generates an active high pulse which will trigger remote modules. Gating – The front panel control on the NL412 provides control for output pulse durations over the range of 1 to 10 ms.Setting this control allows different durations of trains of pulses when the NL412 is combined with a the NL301 Pulse Generator (see above). Use with NL102G – When used with a NL102G (that incorporates external “Buzz” control circuitry) the duration of the “Buzz” is set by the front panel control.