A multi-purpose instrument which is invaluable in the physics laboratory, combining the functions of a multi-purpose timer, a ratemeter and a frequency meter in one compact and economical unit. Its uses are many and varied covering a wide area of the physics syllabus.
Uses in the timer mode range from a simple stopwatch to more sophisticated applications such as dynamics experiments with air tracks etc. The scaler and ratemeter modes allow numerous radioactivity experiments to be undertaken, for example, variations in background radiation, half-life determination and investigation of absorption coefficients. When used as a frequency meter the instrument will accept diversified waveforms and may be used, for example, to determine the rotational frequency of a stroboscope disc and for displaying the frequency of a waveform from a signal generator. It has four, 7-segment LED digits, 13mm high. The high brightness and large size display make it ideal for classroom demonstrations.
The microprocessor based design minimises the number of controls required and these are clearly labelled so that the instrument is very straightforward to use. A single biased-off double throw switch enables RESET or HOLD to be momentarily selected. The HOLD position halts the display whilst the internal timing or counting continues. The instrument, when used as a timer can be switched mechanically or electrically by connecting to one or both pairs of 4mm sockets, labelled ‘A’ and ‘B’. The ‘A’ sockets operate on a rising edge and the ‘B’ sockets operate on a falling edge enabling start/stop operations to be performed from a variety of switch combinations.
Besides use as a standard electronic timer, the instrument can be pulse operated to enable moving bodies to be timed using phototiming gates. When used as a scaler or ratemeter the input signal can be via either a GM tube or a solid-state detector. The GM tube is connected via a TNC coaxial socket and with the switch set to ‘GM’ the EHT supply is continuously variable over the range 300 to 500V. With the switch set to ‘SS’ the pre-amplifier is switched in. The solid-state detector is connected using a BNC coaxial socket. When used as a ratemeter an audio output can be obtained.
For frequency measurements the input is via the pair of sockets labelled ‘A’.
An illuminated on/off switch is mounted on the rear panel adjacent to a fused appliance inlet. The unit is built into a robust metal case with a durable powder coated finish.