Curent Events, Electricity, Electronics, Engineering, Physics, Simon's sketch book, Together with sis

Discussing the news: dangers of shorting your mobile

Today we have heard about a new accident involving a teenager electrocuted by her mobile phone. Luckily, this time it was not a lethal case, but a quick search on the web has revealed that this is no joke: several teens have died in just a few years because they were either holding their phone with wet hands while the phone was being charged at the same time, or dropped their phone into the bath tub while the phone was plugged in, or because they were using wired headphones while charging their phone!

At first Simon and I didn’t believe this could be so dangerous, as he knew for sure that a mobile phone adaptor always has a voltage control built into it that reduces the voltage from 220V to something like 5 to 20V. But then we dove into it and found out that apparently, once a short circuit occurs, the adaptor’s voltage control unit also malfunctions and lets the 220V current through!

Simon’s drawing of the adaptor

Crafty, Electricity, Electronics, Engineering, Experiments, Geometry Joys, Notes on everyday life, Physics, Simon teaching, Together with sis

Vanishing Letters

Simon’s way to celebrate Helloween: a little demo about how red marker reflects red LED light and becomes invisible. A nice trick in the dark!

We also had so much fun with the blue LED lamp a couple days ago when Simon discovered that it projects perfect conic sections on the wall! Depending on the angle at which he was holding the lamp, he got a circle, an ellipse, a hyperbola and a parabola! Originally just a spheric light source we grabbed after the power went out in the bathroom, in Simon’s hands the lamp has become an inspiring science demo tool.

Computer Science, Crafty, Electricity, Electronics, Engineering, Logic, Milestones, motor skills, Simon teaching

Simon building an 8-bit Computer from scratch. Parts 1 & 2.

Parts 1 and 2 in Simon’s new series showing him attempting to build an 8-bit computer from scratch, using the materials from Ben Eater’s Complete 8-bit breadboard computer kit bundle.

Simon is learning this from Ben Eater’s playlist about how to build an 8-bit computer.

In Part 1, Simon builds the clock for the computer
In Part 2, Simon builds the A register (more registers to follow).
these little black things are an inverter (6 in one pack), AND gate and OR gate (4 AND and OR gates in one pack)
this schematic represents the clock of the future 8-bit computer
Simon and Neva thought the register with its LED lights resembled a birthday cake
Electricity, Electronics, Logic, Simon teaching

Simon has been bitten by the hardware bug again!

It’s all Ben Eater‘s fault! Simon is more of a software and pure math champion, but Ben Eater’s videos have sparked Simon’s interest in logic and electronics, anew. Back in mid July (yes, I know, I’m a little behind with the blog), while waiting for his Complete 8-bit breadboard computer kit bundle to arrive from the US, Simon was playing with virtual circuits that he built on two wonderful platforms: Circuitverse.org and Logic.ly. You can view Simon’s page on Circuitverse at https://circuitverse.org/users/7241

Simon’s favourite was building the Master-Slave JK Flip-Flop https://circuitverse.org/simulator/edit/20037

Simon gave me a whole lecture on the differences between Sequential and Combinational Logic: in the former, there’s a presence of a feedback loop (the output actually goes back to somewhere else in the circuit), and the latter has everything going in one direction (the inputs come in and the outputs go out).

It’s a little bit like the difference between a Feed Forward neural network where the output only depends on the input and a recurrent neural network where the output also depends on what the output was previously,

Simon explained.

Here’s a problem with sequential logic circuits: they go crazy like this very often (confused NOR gate). That’s why most sequential logic circuits have a clock in them. A clock acts like a delay so that it won’t go crazy.

That’s the power of sequential logic: you can have the same input but a different output. This is useful for storing data: I release the input, but the data is stored. It can only be archived in sequential logic.

The delay comes in error detection (on the rising edge of the square wave).

Master-Slave JK Flip-Flop
https://circuitverse.org/simulator/edit/20037

The following circuits are buit in Logicly https://logic.ly/demo

SR Latch in Logic.ly
D Flip-Flop
SR Flip-Flop
Master-Slave JK Flip-Flop
Simon building circuits together with his uncle whom he has met for the first time (Russian)
Electricity, Experiments, Physics

Physics Experiments: Using an LED backwards

We have tried using an LED backwards: not get it to shine by letting an electric current pass through it but produce electricity by shining light on an LED (this is how solar panels work). It’s important to use a sensitive LED for this experiment, and as we have observed, it also seems to be important to use light photons of the same frequency as the colour of the LED (red laser didn’t work on a white LED, but it may have to do with the fact that red light is weaker than white light anyway, i.e. has a lower frequency). The picture below shows us measuring the voltage of the current produced by the LED.

shining a light at the diode produces voltage
the same experiment setting but with the light source turned off produces no voltage
red light not strong (energetic) enough to produce voltage, also when shined on a red LED

We’ve have learned this and a a lot more from Steve Mould’s video on How diodes, LEDs and solar panels work: Photovoltaic cells and LEDs are both made of diodes. Diodes are designed to allow electricity to flow in one direction only but the way we make them (out of semiconductors) means that can absorb and emit light.

In the video, Steve shows how the semiconductor atoms share elctrons. Semiconductors are crystal structures of atoms are replaced by the atoms of neighboring elements, for example a structure where some silicon (Si) atoms are replaced by phosphorus (P) or boron (B) atoms, thus providing for free electrons inside the structure (N-type conductor) or for free “holes” unoccupied by electrons (P-type conductor). A diode is basically two semiconductors pushed together. With enough voltage, the electrones are able to jump from the N-type semiconductor across the depletion zone and into the P-type semiconductor, emitting light (photons) as they fill the holes and go from a high energy state into the low energy state.

If you shine a light at a diode, you can kick some electrons from their shells and thus create free electrons and holes that will move (because of the electric field in the depletion zone) and generate voltage.


chemistry, Electricity, Experiments, Physics, Together with sis

How much iron is there in your favorite cereal?

If you put a cereal flake in a bowl of water you can steer it with a strong magnet. The magnets above aren’t strong enough, but the really powerful ones below (that are dangerous to pull apart as they can actually injure you) are:

And if you grind the cereal into powder, the powder sticks to the magnet because of the iron atoms in the cereal:

Inspired by the Veritasium channel.

chemistry, Electricity, Experiments, Milestones, Physics, Simon teaching

Experimenting with electromagnetism

Here Simon tried to induce a magnetic field by allowing electric current to go through a conductor that is normally not magnetic (copper wire). The green stick is a magnet that got attracted to it once the circuit closed.

The copper wire also began to slightly attract the steel paperclips.

Electricity, Experiments, Good Reads, Group, Milestones, Murderous Maths, Notes on everyday life, Physics, Together with sis, Trips

The Maisie Day

For Simon and me, this book (“Infinite Lives of Maisie Day” by Christopher Edge) has probably been one of our most profound experiences of the year. We read it together, sometimes, giggling with joy as we recognized Simon’s favorite topics interwoven in the plot (like that the main character also dreams of proving the Riemann hypothesis), and sometimes tears choking our throats as we went through the sad and scary bits of the story. And what a trip down the memory lane last night, at the Royal Institution in London, where we attended a lecture about the science behind “Infinite Lives of Maisie Day”! As Simon proudly told one of the lecturers (University College London’s cosmologist Dr Andrew Pontzen) after the show, he even predicted something important in the book. Simon recognized that Maisie turned into a mirror image of herself after she had traveled around the Mobius-shaped universe, just as depicted in Escher’s “the impossible staircase” painting . “But that’s only possible if you’re flat, a 2D object! So it’s not correct in the book, but they probably put that in to make it simpler,” Simon laughed. “You’re absolutely right! Keep doing science!” the cosmologist told him. @Ri_Science

Arduino, Coding, Electricity, Electronics

Arduino to relax

Last week Simon suddenly unpacked his old electronics sets and completed several projects with Arduino, his old single-board friend that got him into coding a little over a year ago. Back then it was the most difficult stuff he had ever tried, his first “setups”and “draws”, his first dive into serious circuits. Now Arduino (and iCircuit) is something he does while taking breaks from the real studying/ coding. Amazing how skillful he has become in assembling the circuits, too. All those little wires. Especially considering he still isn’t an expert at tying his shoelaces.

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Coding, Electricity, Electronics, Physics

Back to circuits

Yesterday Simon asked me to buy new electronics software he found on the internet. It’s a realtime circuit simulator and editor called iCircuit. Simon has already built several circuits in it last night and there is so much more to discover. He was following Derek Banas’ tutorials on electronics.