THE READINGS on many types of electronic measuring and recording instruments may be significantly altered by fluctuations in the voltage of the power supply. Inadequate grounding is another frequently encountered difficulty in the use of electrical devices. That such factors must be considered, especially in work of a research nature, where accuracy is important, has been pointed out previously for the case of the electronic tonometer.*
There has been developed at this laboratory a combined unit for standardizing tonography records which will maintain a stabilized voltage to within 0.5% (satisfactory for most medical purposes) and will also provide a simple test for the adequacy of an external ground connection (Figure). A voltmeter on the front panel indicates either the incoming voltage or the stabilized output, and an ammeter shows whether the current load of the attached instruments is excessive. (It may also serve to demonstrate whether the attached instrument is
ASKOVITZ SI. VOLTAGE STABILIZER AND GROUND-TESTING UNIT FOR USE WITH ELECTRONIC INSTRUMENTS. AMA Arch Ophthalmol. 1954;52(1):127–128. doi:10.1001/archopht.1954.00920050129016
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