A general purpose scaler-timer suitable for radioactivity counting utilising Geiger-Muller tubes; and as a general purpose millisecond digital timing device with manual or electronic triggering. The bright L.E.D. has six digits, 24mm high, making it suitable for individual use or for class demonstrations. In the radioactivity mode there is an adjustable 300 to 500V E.H.T. supply for G.M. tubes. Loudspeaker sockets are also provided for use when an audible indication of count rate is required. In the radioactivity mode, the display features 'most significant figure' blanking. In the timing mode, the display reads in seconds, i.e. from 0 up to 999.999s, and increments in ms. This provides a clean, unambiguous display. Timing can be actuated manually or by light operated or mechanical switches and also incorporates triggered timing. Supplies of 2V and 6V a.c. at 0.5A are provided via front panel sockets for optical switch light sources, etc. Display: Six-digit 24mm bright L.E.D. Timing Oscillator: 1000Hz (1ms period) ±0.5%, typically ±0.2%. Reset: push button. Radioactivity Inputs: GM tube via BNC socket with integral 300-500V. supply via directly calibrated rotary control. Timing inputs: (1) Manually switched start/stop; (2) Light gate operated start/stop; (3) Mechanical switch closure start/stop; (4) Triggered timing start/stop (i.e. momentary interruption of light beam). Outputs: 2V and 6V, 0.5A a.c.; Loudspeaker output via 4mm sockets. Mains Supply: 100-120V or 220-240V, 50-60Hz via detachable three-core mains lead with I.E.C connector and moulded on mains plug (240V version). Power Consumption: 8W. This device is compliant to EN61010-2010 with certificates available on request. Dimensions: (W)380mm x (D)140mm x (H)165mm. Full Notes for Use included. Related products include: Geiger-Muller Tube (B8H27155) & Geiger-Muller Tube Holder (B8A49724). Radioactive Source Handling Tool (B8A49608). Radioactive Sources (B849589, B8A49578, or B8A49591).