I needed to synchronise with a variable ac voltage source, without loading it very much – the source is both variable frequency and variable voltage. So I knocked up this circuit (note, right, pnp collector resistor actually 2k2, primary decouple actually 470nF. All passives subject to optimisation) UPDATE: Later, this isolated zero crossing detector got an improved circuit and a ...
Two weeks ago, I had never heard of urethane drive belts, and now I own one, and potentially, many. In need of a drive belt, googling around revealed this (right) un-reinforced stuff, which comes in many diameters and any length. Among other options, there are: orange smooth imperial sizes green textured metric sizes Amazing thing one, is that this stuff ...
Prompted by wise commenter of this parish Steve Kurt, I came across an excellent on-line app note by Texas Instruments (‘SSZTBC7’, by John Betten) about a step-by-step route to effectively snub voltage ringing at buck converter switch nodes. This ringing occurs after the power transistor is switched off, and is the result of residual energy, stray inductance and stray capacitance. ...
Harmonic gearing, aka strainwave gearing, is wonderful stuff – achieving a high gear-down ration is a small space by forcing a bendy gear to mesh inside a larger internally-tooth gear by distorting it from the inside. While the above description is inadequate, this video from Igus explains all. Igus makes plastic strainwave gear boxes for interfacing NEMA 17 size stepper ...
For a long time, I have had books 2 and 3 of Analog Circuit Design at home. These are essentially collections of Linear Technology app notes and, amongst the writings of other authors, there are gems by the great applications engineer Jim Williams. Anyway, a covid-19 lock-down treat, I bought myself volume 1 – for around £40 second hand – ...
John Michell was apparently the first person to propose the existence of black holes, a long time before Einstein – in 1783. I discovered this following mu lock-down tidy-up which revealed Adam Hart-Davis’ (and Paul Bader’s) book ‘The local heroes book of British ingenuity’ – great book 🙂 According to that other great book: Wikipedia, Mr Michell did a heck ...
After a frustrating hour in the workshop with cable ties and bits of wood, trying to ‘quickly’ align a slotted opto-switch with a motor and shutter, I gave up and went to bed…. … only to be visited by a revelation: ‘3d print your way out, idiot’ said the voice in my head*. So: 40 minutes on the computer the ...
Alps Alpine put out a press release to say that it has had to ramp up production of its EM11B front panel rotary encoder because of all the ventilators being made as a result of covid-19. So I had a look as the data to see why this part would be used, and it turns out to be interesting. Firstly, ...
Nordic Semi has put onto its website a simple clear introduction to Thread networking Essentially, it is Internet protocol over 802.15.4 mesh networking – backed by a lot of the big guys. The Nordic Thread information is here
EPFL in Switzerland has created versatile cube robots that can attach themselves to each other to make many structures and do many things. They are ‘Roombots’, and the render (right) is of them being furniture. There is also a video of them carrying other furniture, and then being a robot arm and picking stuff up. The video is cute, and ...
