A low-cost, high-precision scope calibrator. A delayed pulse generator with an isolated output.

A simple scope calibrator for voltage and time calibration is described. A square pulse of calibrated amplitude and pulse-width can be triggered in synchrony with CRO sweep, and displayed, with an adjustable delay, simultaneously with biological signals on CRO screen. The output of the device is isolated from ground and has a low output impedance (less than 50 omega for most ranges). Both the amplitude (10 muV--1 V) and pulse-width (0.2--1000 ms) of the outputs cover wide ranges in 1--2--5 steps with an accuracy of less than +/- 1%. The output drifts against changes in power supply and temperature are negligibly small. The circuit is designed to give the high performance at reasonably low cost, and to be built with only the components readily available in the market.