A device for detecting and counting electrical spikes or transients.
Such spikes can damage equipment, particularly those containing electronic devices.
The test device is contained in a substantial metal enclosure, and powered by three PP7 9 volt batteries.
This video provides an overview of the device, and a detailed look inside.
The case is plywood with a leather strap handle and a metal fastening clip.
There are two modes - Single where a single pulse is detected and indicated by the orange lamp, and Count where multiple pulses are counted on the mechanical counter in the centre window.
The Reset button resets both the counter and the orange lamp indicator. The actual trip level is set using the large centre multi-turn dial, and a smaller control is provided for zero adjustment.
The back panel has a summary of the operating instructions and specifications.
The clips originally had red and black insulation over them, but this has perished and crumbled away due to age.
The actual wires have very thick insulation, more like tubes of plastic - probably due to the high voltages that this equipment is capable of detecting (up to 5000V).
In this video, the device is demonstrated operating. To avoid damage to this decades old device, it is powered from a current limited bench power supply, and the input signal is derived from a function generator with a maximum output voltage of 20 volts.
These are high quality scans of the original documents supplied with the device.