EGT Thermocouple Circuit Design Tips
Posted: Thu Mar 01, 2012 2:08 pm
EGT sensors require a conditioning circuit, which can be made from discretes, but is best done with a dedicated IC such as those from Analog Devices. The following two documents contain notes on getting the most out of them.
http://www.analog.com/static/imported-f ... AN-274.pdf
http://www.analog.com/static/imported-f ... AN-369.pdf
The AD595 and friends have been replaced with the AD8495 and friends. http://www.analog.com/en/mems-sensors/a ... oduct.html
The supply voltage for these chips is raw 12V because they can handle up to 36V and because the supply doesn't affect the reading, just the range. IE, when your alternator is charging you can hit higher temperatures than when it's not. Having said that, the new device has twice the range of the old one so can hit 1000C on 5V. Thus feeding it 9V or even lower from a tiny smd regulator might be a good idea for consistency sake. On the output you just scale the voltage to 5V from your expected max with a divider and cap it with schottkys in case of a nuclear melt down in the engine bay.
These come in a SOIC8 suitable for a small project like our favourite and currently anonymous one by Dan.
Fred.
http://www.analog.com/static/imported-f ... AN-274.pdf
http://www.analog.com/static/imported-f ... AN-369.pdf
The AD595 and friends have been replaced with the AD8495 and friends. http://www.analog.com/en/mems-sensors/a ... oduct.html
The supply voltage for these chips is raw 12V because they can handle up to 36V and because the supply doesn't affect the reading, just the range. IE, when your alternator is charging you can hit higher temperatures than when it's not. Having said that, the new device has twice the range of the old one so can hit 1000C on 5V. Thus feeding it 9V or even lower from a tiny smd regulator might be a good idea for consistency sake. On the output you just scale the voltage to 5V from your expected max with a divider and cap it with schottkys in case of a nuclear melt down in the engine bay.
These come in a SOIC8 suitable for a small project like our favourite and currently anonymous one by Dan.
Fred.