Hidden Morse Code in Tubular Bells

MadPsy : October 31, 2021 23:32 : Audio, Electronics, Radio

The link between The Exorcist, Amateur Radio and Alan Turing.

A quick look at how the movie The Exorcist from 1973 has links to the late great Alan Turing via Mike Oldfield’s album Tubular Bells, Scotland and Amateur Radio. It’s Halloween so figured why not throw some horror in the mix.

When Mike Oldfield recorded Tubular Bells in 1973 he had no idea his first album on Virgin Records would be chosen as the soundtrack to The Exorcist later that year. Neither did he know that recording with Virgin Records would have an unintended consequence of hiding a secret message which dates back to 1926, shortly after World War One.

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Yaesu WiFi TX and Voltage Sensor for Home Assistant

MadPsy : May 14, 2021 17:52 : Electronics, Radio

A simple and quick project for detecting when a Yaesu transciever is transmitting and feed that status to Home Assistant to then perform actions. This can be used to, for example, automate killing the power if the radio gets stuck TX’ing when using automated digital modes software such as WSJT-X remotely. It can also measure the supply voltage, which is always useful information to know, especially when operating remotely.

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Apple Macbook Logic Board Schematics

MadPsy : March 28, 2016 15:30 : Electronics, OS X

Following on from my post about ASD versions I’m going to add a couple of board schematics to this post. Anyone who has tried to fix a laptop will know getting a free copy of the schematics is half the battle. I have loads of these but this is a good start.

M87 PS

Included in PDF format are Macbook Air A1304 (MLB M96), Macbook Pro A1278 (K24, 820-2530), Macbook M42B,

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Apple Service Diagnostic Versions

MadPsy : March 28, 2016 14:38 : Electronics, OS X

As I kept finding myself hunting for the correct version of Apple Service Diagnostics I needed for which model of Mac, I’ve included a fairly recent list in this post.


Here’s the list of Mac models and required ASD versions…

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The nonsense that is ‘Reballing’ dead GPUs

MadPsy : February 5, 2016 09:26 : Electronics

Reballing GPUs seems to be what all the cool kids are into these days. They make the claim that a dead GPU can be repaired by reballing it. What they aren’t telling you, or don’t realise themselves, is neither did it need reballed nor is it now repaired. Maybe it’s the easy money or maybe they just like the temporary smile on the customer’s face. Lets not beat about the bush though – it’s bollocks and don’t pay for it.


When a high performance chip, such as a GPU, is working hard it heats up. It heats up because it’s drawing high current and the energy dissipates as heat. When it’s off or idle it cools down. Over time this constant change in temperature causes its internal circuitry to start decaying. At high temperatures the tracks (or ‘bumps’) in a flip-chip design BGA chip physically deform and you end up with a dead chip.

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Arduino / Pi: Internet Controllable LED Strip Light

MadPsy : October 29, 2015 15:07 : Arduino, Electronics

For my next trick I thought it would be nice to have a web interface “colour wheel” to control an RGB LED strip light. These are dirt cheap and usually come with a crappy infrared remote control. The real nice part about this is once you have it working you can do almost anything you want with it – make a gradual sunrise light for the dark mornings, a security light, an auto-off night light or simply pick the colour you want your room to be from a smart phone.

LED Strip

The basic idea of this design is to have the Arduino handle the control of the LED strip itself but allow the RGB values to be set via a serial connection. The Pi will be sending the RGB values via USB to the Arduino which in turn will use Pulse Width Modulation (PWM) to set the intensity of each LED.

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Second Arduino Project – Nagios LED

MadPsy : October 27, 2015 00:56 : Arduino, Electronics, RaspberryPi

After the successful first project of getting a PIR sensor to work with Arduino I thought I’d try something a bit more practical and bespoke. The idea with this is you can use the Arduino to change the colour of an LED if there are any critical or warning errors in Nagios Monitoring software.


This time we’re going to get the Arduino to read input over its USB serial interface from a Raspverry Pi and depending on what it receives either make the LED light green or red.

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First attempt with an Arduino Uno board – it worked!

MadPsy : October 27, 2015 00:02 : Arduino, Electronics

This Arduino nonsense is actually pretty neat. It’s a small electronics project board with a programmable chip and a pile of General Purpose I/O pins. You can use it to control or be controlled by pretty much anything. There’s tonnes of examples out there from the simple blinking an LED to the much more complex task of automating the watering and lighting of indoor grows.  The best of it is this thing costs £5 – five pounds sterling, no shit!


Unless I’m horribly mistaken but £5 is also the cost of a lego style knife, fork and spoon set.


Don’t get me wrong these are pretty cool too but you can’t program it to electrocute your mate whenever he gets a quiz question wrong so why bother – get an Arduino instead 🙂

Lets take a look at ‘my first Arduino projects’ or at least ones I’ve managed to get working today…

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What is a Decibel (dB) and why it simplifies calculations and graphs

MadPsy : October 25, 2015 17:10 : Audio, Electronics

I’m going to try and explain what a decibel is and why it is used so often. For some reason it seems to confuse a lot of people, especially when used in sound engineering. As it happens the dB is actually really simple once you understand what it is and why it is used.


The first concept you need to get your head around is a dB is nothing more than a ratio, just like saying a 2:1 ratio to mean two apples for every pear, in other words double the amount of apples for every one pear. Instead of linear scaling like this, in the land of dB’s everything is logarithmic. You don’t need to know what that means you just need to know that it’s a ratio. First off a bit of history.

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Build Pics: G-Sub High Pressure Subwoofer

MadPsy : October 16, 2015 18:39 : Audio, Electronics

Buying speakers is boring, anyone with a credit card can do that. Building speakers is a lot more fun! A year ago a few friends and I decided to build a G-Sub. Here’s the build process in pictures.


Before we start here’s a bit of background on the ‘G-Sub’. Speakerplans.com is a website run by speaker design guru Rog Mogale (Void Acoustics etc). The site contains free designs of various cabinets which anyone can utilise. The G-Sub is a twin 18″ reflex cabinet designed for high fidelity bass at extreme pressure levels. The drivers of choice were Fane Colossus 18XB which are industry standard 1kW (AES) drivers capable of 35Hz – 1kHz with 99dB (1w/1m) sensitivity.

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FM Transmitter with Raspberry Pi

MadPsy : October 13, 2015 22:52 : Electronics, Radio, RaspberryPi

When I first read about this I thought it can’t be real but it is. The Raspberry Pi can be used as a stereo FM transmitter. It’s a pretty nifty discovery which uses a GPIO pin on the Pi to generate spread-spectrum clock signals and outputs FM Radio energy.

Radio Pi FM

There’s no point in me rewording what has already been written so here is the explanation from the guys who discovered it over at icrobotics.co.ukmore »

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Energy Monitor Cacti Graphing

MadPsy : October 11, 2015 20:09 : Electronics, Linux

Using an off the shelf energy monitor you can graph your energy using Cacti. The monitor unit I’ve used here is a Current Cost ENVI. E-On were giving these away for free but they’ve probably stopped that now.


It comprises of a sender unit, with a single phase clamp sensor and an more »

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Virtual Breadboard

MadPsy : October 11, 2015 16:39 : Electronics

I thought it would be nice to perform some simulations using the familiar breadboard format without having to buy all the components.

There’s a few choices but this looks pretty good: https://123d.circuits.io

It couldn’t get much simpler than this example I made to see how it works but you get the idea.


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