The FG 503 Function Generator is designed to operate in a TM 500 series power module. Low distortion sine, square and triangle waveforms from 1 Hz to 3 MHz, are available at the front panel. A +2.5 V square wave trigger also is available at the front panel. Variable dc offset of =5 V is provided. A custom timing switch position is provided. This allows the user to install a timing capacitor for custom tailoring the frequency range of the FG 503. A voltage-controlled frequency (VCF) input controls the output frequency from an external voltage source. The output frequency can be swept above or below the selected frequency, to a maximum of 1000:1, depending on the polarity and amplitude of the VCF input and the selected output frequency. The variety of swept and modulated signals available from the FG 503 make it especially useful for such applications as testing servo-system or amplifier response, distortion and stability. It is also useful for FM generation or as a variable beat-frequency oscillator. The square wave trigger output can be used as a source for TTL logic, or to synchronize an external device such as an oscilloscope or counter.