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Sorry, I’m a s/w, not a h/w guy…. Is there a simple circuit using one of the new ADC channels to measure the 24V current? If there were, seems that would be a good indication of whether a valve is open or shorted, which would be a nice utility to have.
hf
When I originally installed my OSPi hardware I quickly discovered that I had a shorted solenoid, 😳 !!!
The shorted solenoid immediately caused a triac to give all it could until it smoked. 😯
After emailing with Ray, Ray highly recommended that I put a fuse (a one amp fast-blow type) in series to the 24VAC power going to the OSPi.
I’ve not had any more shorted solenoids, but if I ever do, I feel confident the fuse will blow before the OSPi is hurt.
@hf3 wrote:
Sorry, I’m a s/w, not a h/w guy…. Is there a simple circuit using one of the new ADC channels to measure the 24V current? If there were, seems that would be a good indication of whether a valve is open or shorted, which would be a nice utility to have.
hf
Some commercial sprinkler controllers do have a feature which allows them to scan through all connected valves and detect those that are shorted. I don’t know what’s the easiest implementation, but one possible way is to use an additional resistor to form a voltage divider with the solenoid, and detect the voltage on the resistor using an ADC channel. Probably another approach is to add a current limiter circuit to limit the amount of current supplied to each channel. In any case, I am very interested in finding a simple and low-cost way to address shorted solenoids.
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