Engineer in Wonderland

I am leaving this blog to spend more time making things in the workshop and, hopefully, finally mastering FreeCad – amongst other mountains to climb (both intellectual and physical). So this is a message to say goodbye, and to say thanks to all the generous folk who have passed wisdom to me through the comments section over the years – ...

There are easier-to-use alternatives to the thyristor (aka SCR) based mains fed motor controllers used to control  ‘180Vdc’ brushed electric motors. These are mosfet choppers, but they tend to cost over £100 and are often poorly documented as they are made as drop-in replacements for treadmill motor controllers such as the MC2100ELS. Interfacing to them can also be tricky as ...

An isolated dc current sensor is required. Isolation in this case, is from the mains, and it transpires that finding something that will do the job safely is tricky. Three isolated Hall-based current sensing modules are easy to obtain, as far as I can tell, based on: Allegro’s ACS712 or clones Allegro’s ACS758 or clones Winson’s WCS1800 All will work ...

I can’t say that my heart leapt for joy when I saw that Qualcomm had bought Arduino. It is not that Qualcomm doesn’t make great semiconductors, and the first Arduino under the new leadership – Uno Q ** – is a very interesting new product and a great concept. It is because Qualcomm is very different from Arduino, and has ...

Arguably, the ATmega328P is being left behind as ‘the Arduino processor’ because Arduino’s are following the rest of the world and going 32bit. But on the other hand, something simple like an Arduino Nano, or one of its clones, with its small size, low cost and easy programming, is a great little problem-solver if you just need knock up a ...

The Sensiron SHT45 precision temperature and humidity sensor got featured here a couple of years ago, and wonderful Adafruit has picked up on it, and not only produces SHT4x breakout boards (right), but also Python, CircuitPython and Arduino libraries for it. Annoyingly, the chip only has a single I2C address option, but here a second Adafruit product comes to the ...

Desktop cnc cutting machines are following the same path as 3d printers, and might just be reaching the point where one could be useful in a development lab. Suitable hardware is only half the battle, and a vital component will be automated software that turns a design into a pattern of cutting vectors – equivalent to the ‘slicers’ that are ...

Wonderland’s current pwm to voltage converter mini-project is to interface a modern grblHAL cnc board with a late 1990s era thyristor-based motor control board in an milling machine. The board appears to be both sophisticated and flexible – for example, it can use armature voltage or a tachometer for speed feedback, it has several different input options to set the ...

Once more opto-isolators are to be seen in Wonderland. The aim was to see if the faster photodiode types can operate quickly in common collector mode. They consist of an infra-red led and a fast npn transistor with its base connected to a co-packaged reverse-based photodiode. And there are layers and layers of subtly in their operation. The conventional circuit ...

Making beams thicker makes them stiffer, but I had no feel for how much. Some bikes needed hanging up at in a neighbour’s shed, but there was very little vertical space – not even enough to put a 93 x 45mm (‘4×2’) on edge right across. A 145 x 45mm (‘6×2’) held flat was away too bouncy But with the ...