The calibrator can be used to check the accuracy of a time-base generator, as well as to calibrate the input level of amplifiers. The calibrator consists of an NE555 connected in the astable mode. The oscillator is set to exactly 1 kHz by adjusting potentiometer P1 while the output at pin 3 is being monitored against a known frequency standard or frequency counter. The output level, likewise, is monitored from potentiometer P2's center arm to ground with a standard instrument. P2 is adjusted for 1 V pk-pk at the calibrator output terminal. During operation, the calibrator output terminal will produce a 1-kHz, square-wave signal at 1 V pk-pk with about 50% duty cycle. For long-term oscillator frequency stability, C1 should be a low- leakage mylar capacitor.