But to make that measurement you need an amplifier circuit designed for the thermocouple being used. Linear Technology LTC 1049 Low Power Zero-Drift Operational Amplifier with Internal Capacitors ...

The pentode is controlled with the pre-amplified signal and acts as a power amplifier ... up detailed build instructions yet, his simple schematic should be all you need to get started.

This circuit layout produced low distortion, prompting Quad to promote the 303 as “the world’s first low-distortion transistor amplifier”. At the rear of the Quad 303 power amp are the ...