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Xringer · 09-29-12, 09:41 AM

For my systems, I would need a detector to work down to -15 C, so measuring temperatures to detect ice would be difficult.

But seeing ice isn't hard at all.

Here are two examples.

Frost Controls SP-820 for Debron 1052 Optical Sensor | eBay

This sensor is wing mounted. Once ice fills the gap/notch, the Ice alarm triggers.

New Avionics: Introducing Ice*Meister Model 9732-OEM, Aerospace Sensor for embedding into host flight systems
PRINCIPLE OF OPERATION

Ice*Meister Model 9732-OEM ice detecting transducer probe functions as an optical spectrometer. It monitors both the opacity and the optical index-of-refraction of whatever substance is on the probe.

The transducer probe is excited by a microwatt IR LED coupled to the driver plastic optical fiber. A likewise-IR detector is coupled to the receiver fiber which inputs to an op amp and comparators.

The threshold comparators register the IR signal voltage-analog from the op amp.

NO-ICE state is reported back to the op amp as a stable mid-level signal. When the ice detecting transducer probe enters an icing domain, it can attract either rime ice or clear ice.

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I'm pretty sure that I could make a frost sensor using an LED (or laser LED) pointed at a light sensor.
With the light 'beam' going pass the area where frost builds up on my outdoor coil.
I would design the detector circuit so it would send a Frost signal when 70% of signal was blocked by ice or frost.

I would have to insure the beam passed within ~5 mm of the HX coil's outside surface. (near the bottom, where it gets thick).

The ice on the sensor might melt (during defrost) before the HX was completely clear, so a timer might be necessary.

09-29-12, 09:41 AM	#3
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Optical detector 'optical frost sensor'? For my systems, I would need a detector to work down to -15 C, so measuring temperatures to detect ice would be difficult. But seeing ice isn't hard at all. Here are two examples. Frost Controls SP-820 for Debron 1052 Optical Sensor \| eBay This sensor is wing mounted. Once ice fills the gap/notch, the Ice alarm triggers. New Avionics: Introducing IceMeister Model 9732-OEM, Aerospace Sensor for embedding into host flight systems PRINCIPLE OF OPERATION IceMeister Model 9732-OEM ice detecting transducer probe functions as an optical spectrometer. It monitors both the opacity and the optical index-of-refraction of whatever substance is on the probe. The transducer probe is excited by a microwatt IR LED coupled to the driver plastic optical fiber. A likewise-IR detector is coupled to the receiver fiber which inputs to an op amp and comparators. The threshold comparators register the IR signal voltage-analog from the op amp. NO-ICE state is reported back to the op amp as a stable mid-level signal. When the ice detecting transducer probe enters an icing domain, it can attract either rime ice or clear ice. ~~~~ I'm pretty sure that I could make a frost sensor using an LED (or laser LED) pointed at a light sensor. With the light 'beam' going pass the area where frost builds up on my outdoor coil. I would design the detector circuit so it would send a Frost signal when 70% of signal was blocked by ice or frost. I would have to insure the beam passed within ~5 mm of the HX coil's outside surface. (near the bottom, where it gets thick). The ice on the sensor might melt (during defrost) before the HX was completely clear, so a timer might be necessary. __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less.. Last edited by Xringer; 09-29-12 at 09:46 AM..