Seeking something-or-other, I came across a high-side current sense circuit that I had never noticed before. Here it is (right), in an app note for the OnSemi NCP3020A buck dc-dc converter controller, driving a bunch of leds. It is used to turn the normally constant-output-voltage chip into a constant current chip. Q2 to Q5 convert the voltage across Rcs (referenced to ...
Despite being standardised in the late 1800s, BA threads, the British Association threads used in old electrical equipment, including vehicle magnetos, are based on the metric system. A BA0 bolt has is 6mm in diameter, 1mm in pitch and needs a 10.5mm spanner. From here, multiply the pitch by 0.9 to get the pitch of the 1BA screw, and do ...
This is accidentally becoming an epic – exploring the combination of Cree’s high intensity XP-P led and Gaggione’s rectangular beam LLC15E optic. One of the problems of using a new led-optic combination where no specific data is available, is working out the correct distance between the led mounting face and the lens mounting face. Having printed a quick fixed lens ...
Got a chance to design and print a quick lens holder to try the 16mm separation which I calculate should be the correct spacing for the mounted Cree XP-P led and Gaggione LLC15E that have arrived. DesignSpark Mechanical used (still too far down the learning curve to risk FreeCAD), and I knocked some holes in the side of the model ...
Lots of people have attempted to design and build fold-up 3d printers, many of which turn out quite compromised. Now I have seen the first that looks properly competent, and erects into something that prints well – I am guessing at least as well as ~£500 printers. It is a one-off by Kralyn3D, called the Positron, and fits into a filament ...
Thanks to Cree, there are now some XP-P led samples at (virtual) Electronics Weekly Tower. I was dying to experiment on some, and they were proving difficult to buy. They arrived beautifully packaged and even vacuum-wrapped. XP-P is Cree’s high-intensity led for long narrow beams – it has a 9Wmax 1 x 1mm die with no primary lens. My aim ...
Zortrax 3D printing equipment has been used to make pistol grips for French Olympic 10m air pistol shooter Celine Goberville – a multiple world champion and already an Olympic silver medallist. They were printed on an M300 Dual 3D printer by French company Athletics 3D, then vapour-smoothed in a Zortrax Apoller – the smoothing step was applied after Goberville won a bronze ...
Researchers at Washington University in St Louis have engineered bacteria to make ‘polymeric amyloid’, which, spun into fibres, achieved average ultimate tensile strength of 980MPa and an average toughness of 161MJ/m3. Lead by professor Fuzhong Zhang, the team was aiming to create a protein that forms ‘β-nanocrystals’, a significant component of natural spider silk. “Spiders have figured out how to spin ...
There are a bunch of low cost cnc engraving machines loosely called ‘3018’ as they cut material up to 30 x 18cm, and the same parts are used in two smaller sizes down to a 1610. They are not the stiffest machines, but lots of folk are making pcbs on them. Engineer in Wonderland CNC-related blogs are indexed here Something ...
Having thought up and simulated a drive circuit for the synchronous rectifier in a Cuk converter, I thought I would wrap it all up by appling the things I learned to the original circuit – a high-side driver for a buck converter (see diag below). C1 represents the gate of the high-side p-channel mosfet to be switched (C2 is simply decoupling) Update: ...
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