The JIB and J2B Signal Generators, like their well-established forerunners the J1 and J2, are two similar instruments which provide sinusoidal outputs in the frequency range 15c/s to 5 0 k c /s. Two separate output arrangements with continuous level control are provided on each instrument. One output is of 600S2 impedance and isolated from earth, having a maximum output level of 1W; the alternative output has an impedance of 5fi connected to earth and with an output level of at least 500 milliwatts. The JIB version of the instrument uses a calibrated output control to give an indication of output level, while the J2B output level is indicated on a front panel meter . Each instrument contains a resistance-capacitance Wien bridge oscillator which is connected to the output stage via a buffer amplifier . The inherent stability of the oscillator and the use of feedback circuits contribute to an output which is substantially constant over the whole frequency range. Overall distortion at full output power is less than 2% (34dB down on fundamental).