I have described a solution an overheating problem with my IC2200H at Cooling an IC2200H. The Yaesu FT2800M suffers exactly the same problem.
This article describes a thermostatically controlled auxiliary fan to keep the case at a safe temperature.
Above is the test setup: Continue reading Cooling an FT2800M
The Fox flasher MkII is designed to run directly from a 1S LiPo battery at 3.8-4.3V. The battery can be charged by a simple voltage limited charger to 4.1V with a small loss in capacity. This article describes a simple solar charger for such a battery.
The regulator uses a TL431 precision programmable reference in a simple shunt regulator.
Above, the 6V 1W PV array. Continue reading Solar power supply for foxflasher2
This tutorial shows how to explore an inexpensive HMC5883 3 axis magnetometer module with Arduino.
The magnetometer module can be purchased on eBay at very low cost (<$3), and is an ideal educational project for the budding Arduino practitioner.
It is an ideal low cost project for a first exploration of explore I2C, and the basis for a digital compass. This particular module breaks out DRDY which is useful for interrupt driven applications.
Fig 1 shows the test setup:
This tutorial shows how to explore an inexpensive stepper motor and driver board using an Arduino and included stepper library.
The stepper motor and driver board can be purchased on eBay at very low cost, and is an ideal educational project for the budding Arduino practitioner.
Fig 1 shows the test setup:
This project was designed ad-hoc as a learning exercise for a friend who ‘needed’ to acquaint himself with Arduino.
What better than a practical exercise that demonstrates some key advantages and disadvantages of the Arduino environment.
The project was a simple digital thermometer to display normal environment air temperature, say from -20° to 50° using common and inexpensive Arduino hardware with firmware developed on the free Arduino IDE, all using hardware that was on hand. Continue reading Arduino thermistor thermometer – a tutorial
I have a little RC-4 temperature logger which has been a really handy device for ensuring that our freezers are cold enough, but no colder.
The RC4 has an internal sensor and is supplied with an external sensor that plugs into a 2.5mm TS jack on the side.
This article explores an alternative sensor that could be embedded in equipment of interest. The sensor is a NTC thermistor.
Firstly, I found that none of the 2.5mm TS plugs I had connected to the RC4 properly, but the T-R of a TRS plug worked reliably.
The display was observed with two 0.1% precision resistors and the thermistor characterised.
Above, it looks like nominally a 110k/B=4200 thermistor… which is a little unusual. 100k thermistors with B=3950 and 4200 are fairly easy to obtain though.
Above is a chart of the error in using the two commonly available thermistors. At low temperatures the 100k/4200 isn’t too bad, around 60° the 100k/3950 is better.
It is a simple matter in Excel to correct readings made with a different thermistor. Here is a VBA function to perform the conversion.
Function temp2temp(ft, ft0, fr0, fb, tt0, tr0, tb) 'function to correct temperature reading to a different thermistor r = Exp((1 / (ft + 273.15) - 1 / (ft0 + 273.15)) * fb) * fr0 temp2temp = 1 / (1 / (tt0 + 273.15) + Log(r / tr0) / tb) - 273.15 End Function
You could squeeze all this into a cell formula if you wished to avoid using a VBA function.
Above is an example measurement run made with a 100k/3950 sensor (Indicated) and the corrected data in brown.
I have evaluated three different series of STC 8051 architecture MCUs, the STC89S52RC, STC15F104E, STC15F204EA.
English documentation is hard to find, and in some cases the translation from Chinese to English is poor and diagram annotations (eg flow charts) are still in Chinese. Continue reading An experience with STC 8051 microcontrollers
Fox flasher MkII described a LED driver for an animal deterrent using a Chinese 8051 architecture microcontroller, the STC15F104E.
Above, the schematic. A very simple circuit with just a handful of electronic components (one capacitor, two resistors, one LDR, one Polyswitch, 4 x LEDs and the MCU). Continue reading Fox flasher MkII #3
Fox flasher MkII described a LED driver for an animal deterrent using a Chinese 8051 architecture microcontroller, the STC15F104E.
Above, the schematic. A very simple circuit with just a handful of electronic components (one capacitor, two resistors, one LDR, one Polyswitch, 4 x LEDs and the MCU). Continue reading Fox flasher MkII #2
This is a review of an inexpensive 8010F Chinese bang-bang thermostat that was purchased on eBay for around A$13 complete with thermistor sensor and postage.
Above is the front view of the thermostat. There are many thermostats on the market with similar front panels, but they differ in internals and most importantly, performance and quality.
Above, the rating label is clear and informational. Continue reading Review of inexpensive Chinese thermostat – 8010F #2