The A6902B Isolator is a two-channel instrument which will permit safe floating measurement of voltages up to 3000 V (dc + peak ac) above and below ground. It substitutes for the vertical amplifier of an oscilloscope when either high-voltage signals or small signals at a high voltage level are to be measured. These signals are isolated from the oscilloscope by a combination of optical and transformer coupling. This type of isolation, together with the all plastic construction of the external controls, protects the operator from exposure to high voltage levels when making control settings of the front panel.