Timeline for Detect 2 wire thermostat output
Current License: CC BY-SA 4.0
12 events
| when toggle format | what | by | license | comment | |
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| Nov 6, 2020 at 8:57 | comment | added | zip85 | I have built the circuit but analogRead(A0) does not change :/ | |
| Oct 29, 2020 at 20:38 | answer | added | Andre Janssens | timeline score: 1 | |
| Oct 29, 2020 at 6:05 | comment | added | zip85 | @Majenko added D1 but it was working anyway. The heater has a relay so it's on or off. Also added pull-down R2. | |
| Oct 29, 2020 at 6:02 | history | edited | zip85 | CC BY-SA 4.0 |
edited body
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| Oct 28, 2020 at 21:41 | comment | added | Majenko | You should add a diode in reverse in parallel with the LED of the optocoupler. At the moment you're halving the power delivered to the heater. Also the optocoupler may die from the reverse voltage of AC. That is if it really is AC - you say +24VAC which makes no sense - there is no + in AC, only DC. | |
| Oct 28, 2020 at 6:35 | review | Close votes | |||
| Nov 13, 2020 at 3:08 | |||||
| Oct 28, 2020 at 3:29 | comment | added | zip85 |
@jsotola Your opto solution worked! I have used an optocoupler in series with a 22k resistor and it does not trigger the heater. I measured the resistance between emitter and collector terminals of the optocoupler. Heater on → 0 (shorted) Heater off → 17Mohm I hope I hooked it up correctly to Arduino to detect it.
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| Oct 28, 2020 at 3:28 | history | edited | zip85 | CC BY-SA 4.0 |
added 68 characters in body
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| Oct 28, 2020 at 2:11 | comment | added | jsotola |
R -----/\/\/\---|>|----- W ... perhaps a high value resistor in series with an LED .... it is possibe that a small amount of current could pass without activating the heater ... the LED would actually be emitter part of an optocoupler ... when the heater is off, the LED is on ... the thermostat contacts short out the LED when they close, which causes the LED to turn off
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| Oct 28, 2020 at 2:01 | comment | added | jsotola | measure the current flowing in the wire | |
| Oct 28, 2020 at 1:57 | review | First posts | |||
| Oct 28, 2020 at 22:29 | |||||
| Oct 28, 2020 at 1:51 | history | asked | zip85 | CC BY-SA 4.0 |