Shop OBEX P1 Docs P2 Docs Learn Events
LM34 temp sensor — Parallax Forums

LM34 temp sensor

MikeSMikeS Posts: 131
edited 2004-11-15 20:05 in General Discussion
I am using an LM34 temp sensor in a project that has a BS2 and LTC1298 enclosed in a box. The top of LM34 is just barely sticking out of a hole drilled in the box. It appears to be reading a couple of degrees higher than it should and I was thinking maybe there was some "Self Heating" because of the·box.

My question is should I have the entire body of the LM34 out of the box?

Comments

  • DaveGDaveG Posts: 84
    edited 2004-11-15 17:40
    Mike,

    I would suggest that you take a look at the spec sheet for the LM34 on the National website. It explains how
    to mount the device to get the best reading. If you are using the TO-92 plastic case version, the primary
    thermal path is through the wire leads, not the case. Therefore you must make sure the leads are
    being heated by the air stream, not by the electronics in the box.

    One trick is to dangle the whole device, leads and all, in the airstream and use small spring-like coils of #30
    copper wire to connect the LM34 leads to your circuitry. The coils provide thermal isolation between the device
    and your warm box.

    Dave G
  • MikeSMikeS Posts: 131
    edited 2004-11-15 20:05
    Dave,

    Thanks for the reply. I Re-read the Spec sheet and found the info you referenced. The "stand off" coils sound like a real good idea.

    Appreciate it

    Mike
Sign In or Register to comment.