@RWB - Absolutely. In fact, from the research my co-worker did, that’s exactly the case (propane if natural gas is not available/if you are “disconnected” from city/town grid)
Most people just use a cheap $1 sonar sensor, the NewPing library and a $4 wifi microcontroller to measure oil level. You can also do this with a Photon. I have maybe a thousand users doing this. VERY popular, and has been for about 5 years now.
There’s not much in the way of design. Connect the sensor, use one of the sample sketches, and expand it to use Photon to communicate. I typically make custom react native mobile apps to interface with my Photon IoT projects to get real-time stats, controls, and notifications.
For an example, I have an Android app on the play store (search for RestroomAvailability) that ties in with Photon. That app uses magnetic switches for input, but it’s just a slight change to interface with a sonar sensor instead.
On the NewPing forum, there’s lots of conversations about using it to measure tank levels. There’s a link to the forum in the above wiki link.
It’s interesting because I know others have done this to measure water levels, but when I searched, I found only 2 people having reported “functional/semi-full” solutions. One guy who did something very similar to me with PVC for the build/mounting + an arduino (if I remember, this was the hack-a-day thing – I also think he ran the sensor to the tank, and everything else was external w/ cat5), and another person who used the cheap ESP8266 but to measure water level in a fish tank. Obviously the concept is the same, but I didn’t really find much around oil – especially the tank measurements encoded (as data/table/function/etc).
To your point - yes, you can get an esp for ~$4-5, but usually from china and then you wait+shipping costs. If you get a ton of them in bulk, it gets closer to $3-4 delivered. I know you can get something like this for $8-9: https://www.amazon.com/HiLetgo-Internet-Development-Wireless-Micropython/dp/B010O1G1ES/ref=sr_1_3, but then you have to deal with everything from wifi connectivity, tethered firmware updates, and writing all of your own REST notifications, variable publishing/retrieval/etc. It’s just too much of a pain for saving $8-10.
For me at least, the Photon is well worth the 40-60% cost purely for the remote API/remote updates/ease of interacting with remote points/REST/etc. If that was not available, I would probably go for the HiLetgo which seems in between the Photon and some of the more “raw” esp8266 (from banggood, ebay, etc)
Anyway, the concept (or code) is not really unique. I was just hoping to achieve 2 things with the project/post:
1.) provide a cheap way for someone to build an attachment for their oil tank (PVC build) which is semi elegant and compcast
2.) provide all of the code so that someone could just copy and paste it and start getting notifications about their oil levels without having to worry about any specifics.
It pained me to see companies charging hundreds of dollars for the hardware solution + a monthly fee (when over ethernet) for the “data/notification service”.
The NewPing library nativity supports Particle, as I’m a Particle Photon user as well.
I would also use a Photon instead of an EPS8266. Also makes it uber simple to make mobile apps/Alexa skills to interface with. But if making a marketable product, EPS8266 would be the way to go to greatly lower costs.
But, HC-SR04 sensors are less than $1 on eBay. An even better sensor is the US-100 at $3. Basically, an entire system can be had for $5 if you know the absolute basics of microcontrollers and programming.
What I and others have experienced is that the US-100 yields better results in worse conditions. For example, when being used as a ground sensor in a quadcopter. The US-100 is a good margin better than the HC-SR04 in this situation. Also, there’s been a TON of defective HC-SR04 sensors in the past as everyone and their brother makes them in China with zero quality control. So the US-100 also work when some HC-SR04’s don’t. I have over 20 ultrasonic sensors and all kinds of different models, so I’ve seen my share of issues.
That’s good to know. Yea, I ran into something similar with the HC-SR04 – the really cheap ones had a huge failure rate (3-4/10). At least most came DOA, versus dying while using them
At the end - I found that the science/lab companies that sold them were pretty reliable. From the last bag I got (I think 8-10), all seem to work so far.
On a different topic - someone on instructable specifically asked about handling calculations in sound variation for extreme temperature drops, so I’ll mention this sensor (US-100) since it has a built-in temperature sensor and automatically handles that.
Made some pretty significant improvements to the code if anyone is following this/has created their own.
summary:
1.) Found a bug in the calculation table - fixed
2.) large cleanup of the alerts and added so that at each level it nulls the previous alerts – just in case you reboot/deep-sleep and flush the previous data
3.) added a re-fill alert, so that you will know when they automatically re-fill your oil
