I had need for a rechargeable CR2 battery. The ‘standard’ CR2 is a non-rechargeable Lithium battery of nominal 3.0V.
I purchased two Ultrafire batteries advertised on eBay as Lithium-ion of 800mAh for $20. Without further qualification, we normally take Lithium Ion to be nominally 3.6V. The batteries are marked Li-ion 3.0V. Continue reading Chinese 3.0V 16340 CR2 Lithium Ion batteries
ESP WiFi relay project – preview previewed a WiFi controllable relay board using commonly available low cost hardware from sources like eBay and Aliexpress.
The stimulus for the project is a remotely WiFi controllable relay for reset function in a remote controlled ham station, basically to recover operation of some system element by bouncing the power.
The information presented here applies to development v0.2.
Features:
Above is a ESP12F_Relay_30A X2_V1.1 relay board (~$20 inc shipping) deployed for field testing. This board has a switched mode power supply on board and will run on 7-28VDC. In this application, the AC circuit is wired through the NC contacts, and the relays are operated to break the power. Normal operation is with the relays released, and current consumption @ 13.8V is 30mA. Continue reading ESP WiFi relay project – update #1
I have lots of projects across a range of microcontroller architectures where reliably programming a new instance of the target is required.
Using an IDE to compile and load, eg traditional / common use of the Arduino IDE, is not a path to that reliability.
A better approach is to save compiled binaries, and have a saved method of programming the chip, binary application code, EEPROM if needed, and hardware settings such as fuse bits, options etc.
Let’s look at an example, a cmd file or bat file to program certain Arduino architecture boards with a customised Optiboot bootloader. Continue reading WriteOptiBoot.bat
The impetus behind the project is a remotely WiFi controllable relay for reset function in a remote controlled ham station.
The information presented here applies to development v0.1.
Features:
Above, a Yunshan relay, not recommended as RESET pin is tied high. This one was binned, quite a waste of money. It exemplifies a common problem in that the RESET line is often not available on a header pin, this one is worse in having tied RESET high and no header pin for EN. Continue reading ESP WiFi relay project – preview
ESP8266 relay module review – Yunshan WiFi relay documented a review of a (at the time) cheap ESP8266 WiFi relay module.
Above, the basic module. Continue reading ESP8266 relay module review – Yunshan WiFi relay – a new life
The DST1020 targets the market for inexpensive digital thermostats, the most popular being the STC1000. There are two novel features to the DST1020:
The DS1820B should be considerably more accurate and overcome the significant error in the conversion of NTC resistance to temperature in the other thermostats (experience is that the approximation used for the NTC characteristic is simple and inaccurate).
It is sold with brief and inadequate / incorrect user instructions.
Above, the front of the DST1020. Continue reading Review of inexpensive Chinese thermostat – DST1020
A friend referred me to a ‘replacement’ for the HC-05 Bluetooth module, a JDY-31.
Above is a JDY-31 bluetooth module with header pins fitted. The physical design is poor, the header pins can be fitted from only one side (not plated through holes, no pads on the other side, probably to suit the base board below), and the black plastic part obscures the board labelling of the pins. Continue reading JDY-31 Bluetooth SPP module
This is a new project derived from IoT water tank telemetry project – part 1 , but using an inexpensive 1MPa 4-20mA pressure transducer.
Above is the electronics and 4MPa pressure transducer fitted with a Nitto male connector for a trial. Continue reading IoT water tank telemetry project – 4-20mA / 1MPa pressure transducer trial
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
I was somewhat frustrated that I could not easily buy air filter foam inserts for the common 25cc Chinese chainsaw. Sellers sold the housing, but no filter element in it.
So, the project is to make a template to cut a foam element that is a neat fit inside the housing.
Above is a sketch laid up over a picture of the filter cover. The template is made a little larger than the aperture so that the foam filter element compresses a little to fit. Continue reading A template for an air filter foam element