OPTOISOLATOR_FOR_PROBE

Published:2009/7/10 22:18:00 Author:May | From:SeekIC

Offsets need for potentially dangerous practice of floating oscilloscope with respect to ground. Also permits simultaneous display of two voltages with correct polarity on double-beam oscilloscope when one of them is floating. Texas Instruments TIL112 optocoupler used has bandwidth of about30 kHz, Three rangesgive choice of 1 :1, 10:1, and 100:1 input attenuation. Set RV2 to bias phototransistor of optocoupler to center of its linear range (about 4.5 V between pins 4 and 5), then set RV1 to give unity input/output ratio on range 1. RV3 is set to give zero DC output when input telminals are shorted, but can be omitted if zeroing of output level is unnecessary.-A. F. Sargent, Simple C.R.O. Input Isolating Probe, Wireless World, Feb. 1976, p 76.



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