MODEL 278 The Model 278, a 0.01 Hz to 12 MHz Programmable Synthesized Function Generator, can operate in continuous, triggered, gated, burst, synthesized, external reference, or external phase lock modes with output levels to 20 volts peak-to-peak. The synthesized mode has 5 digits of frequency resolution with 0.0005% accuracy, or it can be locked to an external 10 MHz (zero-crossing or TTL) frequency reference for greater accuracy and stability. In addition, the separate synthesizer circuit acts as a highly accurate internal trigger source. The generator can produce sine, triangle, square, square complement, and pulse waveforms as well as dc and external width.. Data entry is from the front panel or GPSB (IEEE-488, 1978). Numeric input is entered in free format: fixed, floating, or exponential notation. Parameters may be entered in any order. Internally, all entries are interactively checked for errors and displayed on the front panel, or they may be accessed through the GRIB. Output level is specified from 10 mV to 10 Vp-p into a 500 termination and 20 mV to 10 Vp-p into an open circuit with 3 digits of resolution. Offset can be programmed to vary the waveform base line up to ± 10V, or in the dc function, to vary the dc output. All inputs and outputs are protected against short circuits and excessive voltages between ±15V. The function output is further protected against voltage inputs up to 140 Vac or ±200 Vdc. Activation of the protection circuits will cause a front panel error message and may cause a GPIB service request. Up to 100 sets of complete front panel settings can be stored in memory. The memory has a non-rechargeable lithium battery back up for up to 6 months (typically 1 to 2 years). A “low battery” warning will be indicated on the display when the battery voltage drops to 80% of its normal voltage. WARNING This equipment uses a BR-1/2A, 3V lithium battery, that contains less than 0.3 grams of lithium. To prevent the release of a potentially harmful substance, DO NOT RECHARGE, SHORT CIRCUIT, DISASSEMBLE, OR APPLY HEAT TO THE BATTERY. In addition, observe correct polarity when replacing. instruments manufactured prior to serial number 7230039 may be limited to 40 sets of stored settings without battery back-up. But if an option (previously identified as Option 001) was installed, there will be a total of 100 sets of stored settings with non-rechargeable battery back-up as described in this manual.