Scope’s Time Base Calibrator

A scope calibrator is a circuit that is used for calibrating the variable time base oscillator of general purpose scopes. This scope calibrator gives 100kHz reference, so if the scope is set to 10 cycles on 10 graticule divisions, then each division represents 10 microseconds or 100kHz. And each division will represent 1 Mhz or 1 microsecond if the scope is set to one cycle on 10 graticule divisions. Here is the schematic diagram of the  circuit:

[Circuit’s schematic diagram source: seekic.com]