| 20090215180 | ELECTRONIC CHEMICAL TRACE DETECTOR - A hotplate chemical trace detector comprising a heatable conducting plate with a heater element having a predetermined temperature-power characteristic. A balancing circuit comprises an adjustable resistor for tuning the heater element to a predefined resistor value. A processor is provided for adjusting the adjustable resistor so as to provide a stabilized temperature in said heatable conducting plate and a detection circuit is provided for detecting a change of resistance in the heatable conducting plate in accordance with the presence of a chemical trace reacting in the presence of the conducting plate. According to the invention a test circuit is provided for measuring a dissipated power in the heater element and for calculating a real temperature from the dissipated power in the heater element based on the predetermined temperature-power characteristic. | 08-27-2009 |
