Jump to content

PTC probe extension , considerations

Recommended Posts


I need to run a longer cable from the PTC bricklet to the the PT100 probe (the one from your shop).

I used 2 x1mm^2 sensor cable  to extend the 1m that comes with the probe. 7m long.   

Do you think that can affect the results much?

I have some concerns , as that is an important readout I have 2 sensors in exactly the same location, glued together with a thermal glue into one blob attached to the pipe.

They are about 1-1.1 degree apart, and output looks a bit noisy.  (I read them every 2 seconds)


What do you think?

Link to post
Share on other sites


as far as I understand your description you use a 2-wire probe, right? For a 2-wire probe there is no wire resistance compensation. One possibility would be to connect the 2-wire probe with 4-wires, such that you can compensate for the wire resistance.

Regarding noise a longer cable might induce more noise. In this case a 4-wire connection should also improve the situation.

Link to post
Share on other sites
  • 2 weeks later...

Ok so I rewired the setup and now 2 sensors (Output 1, Output2)  are 4 wire (7m extension).  3 named Noel are old setup (2 wire 7m extension).

And for comparison I added Poiol skimmer to the graph that is same PTC probe on 2 wire directly to PTC bricklet  on the same RPI HAT. 

As you can see the extension is the problem , adding 2 wires did not improve the noise. Probe directly into the bricklet is super clean.

What else could be a problem here?




Edited by xsherlock
Link to post
Share on other sites

Hi Sherlock,

is it possible that you send me a picture of your extension? The connection at the sensor and at the Bricklet is what I like to see.

I'm pretty sure that you have done that right, but sometimes it is much easier to see it on a picture that to explain it by words.

You have configured the PTC Bricklet for 4-wires, right?

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...