EAF Hack

AstroDude42

Very nice, Chen! Invaluable information as always. Your solution is such a relief in regards to cable management that is involved with the original external probe from ZWO. I am already considering exchanging the original probe.

Aloha,
Olli

Astrobert

w7ay
Thank you very much!

Gary7

Hi, Chen
Thanks for the EAF tem probe hack. I assembled two of them using generic 100k ohm thermistors purchase on Amazon
'HiLetgo 10pcs 3D Printer NTC Thermistor 100 K Accuracy 1% B Value Temperature Sensor 3D Printer Parts'
(not sure if secondary vendor links are allowed).
Both of my probe tremperatures report temperatures 7-15 degrees higher than the ZWO extgernal probe- which closely matches 2 digital thermometers that I tested it with. I soldered to the tip and sleeve, carefully avoiding the ring tip and any other conttact.

Could you refer me to the correct thermistor? The generic ones I see are for 3D printers; perhaps the ones I purchased are all junk.

Many thanks,
Gary R.

w7ay

Gary7 HiLetgo 10pcs 3D Printer NTC Thermistor 100 K Accuracy 1% B Value Temperature Sensor 3D Printer Parts

That is what I'd used.

Currently, one of them is showing this, with a La Crosse outdoor probe about 10 or 15 feet away.

Use an ohmeter to double check if Amazon shipped you the correct part.

Chen

Lain402

w7ay I also made my EAF temperature probe following your instructions and it works perfectly !

Thank you Mr. Chen !

Eikie

Created an account just to tell you it indeed worked. So thanks....

Bought the exact items you specified from aliexpress and even with my wonky soldering skills it worked great....

1WGe88Ye

Nifty! I just finished my first one and it appears to be working well. Two to go. Thanks for sharing.

SebE

Thanks a lot for this amazing 'hack'
I did it and it's just works as expected
better than long cable and internal temp

t8481ikU

I know this is an old thread, but I'm putting together the probe as described by Chen, but with a headphone jack that has three connectors: left, right and ground. how would you connect the two-wire thermistor? Thanks.
Mike

Luxo

It’s described in the first post - connect to the tip and the bottom sleeve. The ring in the centre is not connected.

t8481ikU

Thanks, Luxo. Yes, I read Chen's first post a number of times. I had to use a multi-meter and check continuity to make sure which of the two prongs was tip. The probe works but does not read anywhere near the correct temperature. Ambient was 20.4C, probe readout was 30C. When I disconnected the probe, EAF internal sensor temp readout was 26.8C. So, internal EAF sensor was closer to ambient than the probe. Any ideas? Thanks.
Mike

Luxo

t8481ikU
Mike,

What you want is a sensor that reports changes in temperature reliably - especially to trigger autofocus.

Whether the actual value it reports is accurate is somewhat irrelevant (ie doesn't matter) - all that means is that the thermistor isn't well calibrated - which you won't get from a thermistor bought at random. But it will still report changes fine.

For the ZWO sensors there is probably a calibration done.

WKYhgnu5

Thanks Chen. I just ordered the parts. I'm hoping the focuser is sending the temp to the ASIAIR, and the ASIAIR will stop exposures while refocusing, then start again? Thanks for the hack

t8481ikU

Yes, I was aware that the relative change in temp is what is important. Interesting about the calibration. In any event, I ditched the whole approach and have configured my imaging program to use the environmental sensor from my Pegasus PPBA for temperature-based focusing. It is highly accurate. Thanks for your help, though. Much appreciated.
Mike