Hi Richard,
have you read section 2.2 of this appnote?
sloa277a.pdf
By the way, which LM324 are you using? The original LM324-N from National Semiconductors or the clone from TI?
Kai
to User473,
I searched all the op amp portfolio with the parametric search (precision, general purpose, and high-speed). There are 6 options with temperatures of 150C and above (see attached). The best match is the OPA211-HT (210C max). This is the…