Hello,
I am searching for a binary sensor which reads the current status of my air conditioning unit. The current out is via 6 LEDs running on 24V DC.
How can I read these?
An ESP runs on 3-5v. Can I just use a DC-DC convert like the MP1584EN DC-DC and put in parallel to the LED?
Thanks!
Regards Wolle
One of these if the signal level is 24V.
However if you measure the voltage across the LEDs you will find it is quite low (1.5 to 3v depending on the colour). Most of that 24V will be dropped across a current limiting resistor.
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Use optocouplers. Solder optocoupler photodiode parallel to led diode, use phototransistor side as switch which shorts esp32 input to the esp32 ground. So, six optocouplers should do the trick.
Do not do this if you want to continue to see the LEDs.
The Optocoulpler internal LEDs will most likely have a lower Vf than the the aircon LEDs preventing the aircon LEDs from turning on.
Agree. But with additional resistor in serie with optocoupler diode should work.
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Maybe, if you use a very small one (there’s already a current limiting resistor in series with the aircon LEDs). Now it’s getting messy though, unless you are a free-form soldering wizard it would be much easier to use the board I linked to above. It’s about as cheap as buying the optos separately and much easier to connect.
This board is elegant solution, can’t argue with that.
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Thanks!
The air conditioning uses a Gira Touch sensor with integrated status LEDs. So the touch sensor should have an integrated resistor to reduce the voltage for the LEDs.
Gira 20011210
https://katalog.gira.de/de_DE/datenblatt.html?id=653059
