Playing with the PhotoSynTheremin Kit by Citrus Circuits 🍊⚡

https://makertube.net/videos/watch/edf155d6-7bed-44a1-90d5-65184f67d685

Beautiful Engineering In This Laser Unit From a Tornado Jet Fighter

Those of use hailing from the UK may be quite familiar with the Royal Air Force's Tornado fighter jet, which was designed to fight in a theoretical nuclear war, and served the country for over 40 years. This flying deathtrap (words of an actual serving RAF fighter pilot this scribe met a few years ago) was an extremely complex machine, with state-of-the-art tech for its era, but did apparently have a bit of a habit for bursting into flames occasionally when in the air!

Anyway, the last fleet is now long retired and some of the tech inside it is starting to filter down into the public domain, as some parts can be bought on eBay of all places. [Mike] of mikeselectricstuff has been digging around inside the Tornado's laser head unit, which was part of the bomber's laser-guided missile subsystem, and boy what a journey of mechanics and electronics this is!

Pulse-mode optically pumped YAG laser

This unit is largely dumb, with all the clever stuff happening deep in an avionics bay, but there is still plenty of older high-end tech on display. Using a xeon-discharge-tube pumped yttrium aluminum garnet (YAG) laser, operating in pulsed mode, the job of the unit is to illuminate the ground target with an IR spot, which the subsequently fired missiles will home on to.

Designed for ground-tracking, whilst the aircraft is operating at speed, the laser head has three degrees of moment, which likely is synchronized with the aircraft movement to keep the beam steady. The optical package is quite interesting, with the xeon tube and YAG rod swimming in a liquid cooling bath, inside a metal housing. The beam is bounced around inside the housing using many prisms, and gated with a Q-switch which allows the beam to build up in intensity, before be unleashed on the target. Also of note is the biggest photodiode we've ever seen -- easily over an inch in diameter, split into four quadrants, enabling the sensor to resolve direction changes in the reflected IR spot and track its error. A separate photodiode receiver forms part of the time-of-flight optical range finder, which is also important information to have when targeting.

There are plenty of unusual 3-phase positioning motors, position sensors, and rate gyros in the mix, with the whole thing beautifully crafted and wired-up military spec. It is definitely an eye opener for what really was possible during the cold war years, even if such tech never quite filtered down to civilian applications.

We've seen a few bits about the Tornado before, like this over-engineered attitude indicator, and here's the insides of an old aircraft QAR (Quick Access Recorder)

Thanks [Zane] for the tip!

#teardown #weaponshacks #laserrangefinder #optical #photodiode #tornado #yaglaser

IR Translator Makes Truly Universal Remote

Universal remotes are a handy tool to have around if you have many devices that would all otherwise have their own remote controls. Merging them all into a single device leads to less clutter and less frustration, but they are often not truly "universal" as some of them may not support every infrared device that has ever been built. If you're in a situation like that it's possible to build a truly universal remote instead, provided you have a microcontroller and a few infrared LEDs on hand.

This was the situation that [Matt] found himself in when his Amazon Fire TV equipment control feature didn't support his model of speakers. To get around this he programmed an Arduino to essentially translate the IR codes from the remote and output a compatible set of codes to the speakers.This requires both an IR photodiode and an IR LED but little else other than the codes for the remote and the equipment in question. With that all set up and programmed into the Aruino, [Matt]'s remote is one step closer to being truly "universal".

While [Matt] was able to make use of existing codes in the Arduino library, it is also possible to capture the codes required manually by pointing a remote at a photodiode and programming a microcontroller to capture the codes that you need. [Matt] used a Raspberry Pi to do this when debugging this project, but we've also seen this method used with a similar build which uses an ESP8266 to control an air conditioner via its infrared remote control capabilities.

#microcontrollers #arduino #control #infrared #ir #photodiode #raspberrypi #remote #translator

A Trio Of Photodiodes Make A Radiation Detector

The instinctive reaction when measuring nuclear radiation is to think of a Geiger counter, as the low-pressure gas tube detectors have entered our popular culture through the Cold War. A G-M tube is not the only game in town though, and even the humble photodiode can be pressed into service. [Robert] gives us a good example, with a self-contained radiation detector head that uses a trio of BPW34s to do the job.

At its heart is a transimpedance amplifier, a not-often-seen op-amp configuration that serves as a very high gain current-to-voltage converter. This produces a spike for every radiation event detected by the diodes, which is fed to a comparator to produce a logic pulse. The diodes require a significant bias voltage, for which he's used 48 V from a stack of 12 V photographic dry cells rather than a boost converter or other potentially noisy power supply. Such a sensitive high-gain device needs to be appropriately shielded, so the whole circuit is contained in a diecast box with a foil window to allow radiation to reach the diodes.

This isn't the first BPW34-based radiation detector we've seen, so perhaps before looking for a Cold War era relic for our radiation experiments we should be looking in a semiconductor catalogue instead.

#science #toolhacks #photodiode #radiationdetector #transimpedanceamplifier