Oxygen monitoring circuit with built in testing means
US4223549A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 16, 1979 |
| Grant date | Sep 23, 1980 |
| Priority date | — |
| Expiry date | Feb 16, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/4175
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An oxygen monitoring circuit is disclosed. The circuit comprises a high impedance follow and hold circuit adapted for connection to an oxygen probe, a readout unit connected to the high impedance follow and hold circuit, a programmer normally connecting the oxygen probe to the high impedance follow and hold circuit but momentarily disconnecting the oxygen probe from the high impedance follow and hold circuit for a relatively short time interval and loading it with a resistor having an impedance relatively higher than the normal impedance of the probe, and a probe failure indicator connected to the outputs of the oxygen probe and of the high impedance follow and hold circuit for detecting any significant change in impedance of the probe and resistor combination as a result of loading and for operating an alarm when the impedance of the probe exceeds a predetermined value.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.