Yes, a thermocouple is the proper sensor to use here, but a thermistorwill work just fine. In fact, all of the laser printers I have takenapart in my successful quest to print directly on copper have usedthermistors as the temperature sensor in the fuser. Invariably just avoltage divider with the voltage proportional to the temperature and readby an adc. Very easy to implement and very accurate.
Mark
At 02:37 AM 1/2/2017, you wrote:
The transistor is being used asa diode. Iâve seen this on amplifiers to monitor the power transistorsand adjust the bias so it donât go into thermal runaway. In allheater circuits I have dealt with we always used a temperature controlwith a thermocouple. These withstood the higher temperatures . they alsohad some form of high limit protection in case of a shorted thermocoupleor controller failure.if the thermocouple failed open the controllersimply shut the heat off altogether.
From: Homebrew_PCBs@yahoogroups.com[mailto:Homebrew_PCBs@yahoogroups.com]
Sent: Sunday, January 01, 2017 2:12 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: RE: [Homebrew_PCBs] Re: Temp upgrades of lam's HOW highis high heat conditions
A transistor with two of three legs soldered together makes a temperatureprobe. Is
the temperature inside of lam too hot? Google for temperature probecircuits like I
do for other projects.