IoT water tank telemetry project – ultrasonic sensor – #1 described an inexpensive ultrasonic ranging sensor for trial.
Above is a bunch of HC-SR04 ultrasonic ranging sensor. Continue reading IoT water tank telemetry project – HC-SR04 – third trial
Category: Electronics
IoT water tank telemetry project – HC-SR04 – second trial
IoT water tank telemetry project – ultrasonic sensor – #1 described an inexpensive ultrasonic ranging sensor for trial.
Above is the HC-SR04 ultrasonic ranging sensor, it was purchased for around $6 from a local eBay seller and delivered within days. Note that there are somewhat similar looking things with a second board on the back and a different interface, the basic HC-SR04 as pictured suits this project.
In this second trial, the battery saving feature has been activated. It powers the HC-SR04 on for each measurement, waiting 600ms for the HC-SR04 to stabilise. Continue reading IoT water tank telemetry project – HC-SR04 – second trial
IoT water tank telemetry project – JSN-SR04T-3.0 – first trial
IoT water tank telemetry project – HC-SR04 – first trial mentioned an inexpensive ultrasonic ranging sensor for trial.
Above is the JSN-SR04T-3.0, a waterproof transducer on a cable and the electronics board. The protocol is HC-SR04 PWM. No specifications or datasheet were found (other than the seller’s brief description). Continue reading IoT water tank telemetry project – JSN-SR04T-3.0 – first trial
BME280 vs BMP280
Several of my projects use Bosch BME280 sensor chips for measuring temperature, pressure and humidity.
Some correspondents have expressed problems using BME280 modules that they bought online, and it is usually because they have been cheated by online sellers misrepresenting BMP280 as BME280.
My projects that include code to initialise and read BME280 humidity will fail on a BMP280… check to see if the humidity results returned look sane. A driver may read the ChipID and fault on the ID returned by a BMP280.
The Bosch chips are usually visually different, and most clones likewise.
Above, the BME280 is a small square package, about 2.5mm each side. Continue reading BME280 vs BMP280
IoT water tank telemetry project – ultrasonic sensor
The code developed for support of some ultrasonic sensors has been merged into the original tanklevel project at https://github.com/owenduffy/tanklevel. A lot of refactoring to provide to the change.
So far, support is provided for HC-SR04 (and things that emulate its PWM mode), MB1242 (and emulations like GY-US42v2).
A work in progress…
IoT water tank telemetry project – GY-US42v2 – first trial
IoT water tank telemetry project – ultrasonic sensor – #1 described an inexpensive ultrasonic ranging sensor for trial.
Above is the GY-US42v2 ultrasonic ranging sensor, it was purchased for around $14 on Aliexpress delivered within 10 days. Continue reading IoT water tank telemetry project – GY-US42v2 – first trial
IoT water tank telemetry project – HC-SR04 – first trial
IoT water tank telemetry project – ultrasonic sensor – #1 described an inexpensive ultrasonic ranging sensor for trial.
Above is the HC-SR04 ultrasonic ranging sensor, it was purchased for around $6 from a local eBay seller and delivered within days. Note that there are somewhat similar looking things with a second board on the back and a different interface, the basic HC-SR04 as pictured suits this project.
A series of tests were conducted of range to a hard surface at a distance of about 250mm and calculated ‘tank’ level and temperature plotted over time. Temperature is measured on the prototype breadboard using a DS18B20, and calculation of distance is compensated for the variation in velocity of sound with temperature. Continue reading IoT water tank telemetry project – HC-SR04 – first trial
IoT water tank telemetry project – ultrasonic sensor – HC-SR04
This is a new project derived from IoT water tank telemetry project – part 1 , but using an inexpensive ultrasonic ranging sensor to determine the height of water in a tank or dam, and so water depth or volume.
Above is the HC-SR04 ultrasonic ranging sensor, it was purchased for around $6 from a local eBay seller and delivered within days. Note that there are somewhat similar looking things with a second board on the back and a different interface, the basic HC-SR04 as pictured suits this project. Continue reading IoT water tank telemetry project – ultrasonic sensor – HC-SR04
Stacking two ferrite cores of different permeability for an RF inductor
One of the magic ham recipes often proposed is to stack two ferrite cores of different permeability for an RF inductor, but an explanation is rarely offered, I have not seen one.
An explanation
Starting with some basic magnetism…
The inductance of an inductor is given by \(L=N\frac{\phi}{I}\).
For a closed magnetic circuit of high permeability such as a ferrite cored toroid, the flux is almost entirely contained in the core and the relationship is \(\mathcal{F}=\phi \mathcal{R}\) where \(\mathcal{F}\) is the magnetomotive force, \(\phi\) is the flux, and \(\mathcal{R}\) is the magnetic reluctance. (Note the similarity to Ohm’s law.) Continue reading Stacking two ferrite cores of different permeability for an RF inductor
ESP8266 IoT BME280 temperature, humidity and pressure – 06/2021 update
ESP8266 IoT BME280 temperature, humidity and pressure described an IoT project. This article documents an update for newer nodemcu core (NodeMCU 3.0.0.0) and the revised support for BME280 (the older method having been deprecated).
This project is based on ESP8266 IoT DHT22 temperature and humidity – evolution 3, but uses the Bosch BME280 temperature, humidity and pressure sensor. The BME280 has been around for a couple of years, though recently, modules using the chip have become more expensive on eBay, around $10. If you find BME280s listed for much less than that, it is probably Chinese cheats doing a bait and switch… delivering BMP280 (pressure only). Continue reading ESP8266 IoT BME280 temperature, humidity and pressure – 06/2021 update