Resistance to frequency circuit for measuring ambient temperature on a thermostat
US5744973A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 21, 1995 |
| Grant date | Apr 28, 1998 |
| Priority date | — |
| Expiry date | Jul 21, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01K7/245
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A resistance to frequency circuit for measuring the ambient temperature on a thermostat. The temperature measuring circuit comprises a first Schmitt trigger NAND gate, a rectifier, a capacitor of which one terminal is electrically connected to ground, a first resistor, a thermistor and possibly a second resistor. The capacitor is connected with the cathode electrically connected to ground, the anode is electrically connected to the first input of a NAND gate. The output of the NAND gate is electrically connected to the anode of the rectifier. The cathode of the rectifier is electrically connected to both the thermistor and the first resistor. The second terminal of the first resistor is electrically connected to the anode of the capacitor and the first input to the NAND gate. The thermistor is electrically connected to a tri-state buffer of the microprocessor. The circuit uses the open drain output ports of a microprocessor to provide the multiplexer function of the A/D. Two precision resistors are connected to the cathode of the rectifier with their second terminals electrically connected to a second and third tri-state buffer. By selectively switching through the tri-state buffer…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.