Here I tear down a Line Replaceable Unit from a RAF Tornado jet fighter aircraft. A LRU is aviation speak for the black box(es) that sit in the avionics / equipment bay of an aircraft which contain the electronics for the various on board systems and computers. The Tornado aircraft was retired from service in the UK's RAF last year (2019) being replaced by F35's and Eurofighters. The box dates from 1978 / 1979 as it is part of the original avionics suite when the aircraft was put into service. They had an avionics upgrade circa 2000 I believe where the cockpit instruments were replaced with LCD displays rather than analog dials and the navigation system (TARDIS) updated to full colour high resolution LCD's. Now presumably the LRU's were replaced too; I highly doubt there were 1970's electronics still in use onboard an aircraft in 2019! *** UPDATE*** Yes, they were using some of the original avionics up until the aircraft was retired. I found another interface unit on eBay that had the service documentation with it stating the fault and the aircraft it was removed from. It was removed and replacement LRU fitted to the aircraft in September 2018. It is very well engineered and consists of 14 circuit boards that plug into a backplane consisting mainly of analog circuity such as comparators and op-amps with several other boards containing 54 series TTL (military spec of 74 series TTL) which from what I gather form a interface between various sensors and the main computer of the aircraft. This is an" interface 1" LRU; the Tornado had two interface units presumably connecting several systems and sensors to the main computer. The circuit cards contained inside of the interface 1 LRU depends on what model aircraft it came from; there were several variants of the Tornado such as the GR1, GR4 and ADV. I believe this came from the ADV variant as I found the same unit on ebay with a slightly different part number which mentioned the particular aircraft it came from. That was a GR4. Speaking of the main computer I managed to find out that it does not have a CPU, rather it is discrete consisting of several boards packed with TTL logic gates. The avionics were designed in the early to mid 70's when microprocessors were in their infancy. Unfortunately there isn't much information on any of the Tornado's avionics, sources I found were a forum with former service technicians contributing and the Rochester Avionics Archive over at BAE Systems. There are several sellers on eBay selling various Tornado parts. Beware though when buying electronic modules; a lot have had their guts removed so they are literally empty black boxes. The sellers fail to mention this. Anyway, if you do have any information and / or any comments please comment below. Also visit my blog at www.adrian-smith31.co.uk/blog for a detailed article and high resolution photos of the circuit boards. Finally, you may be wondering what on earth I'm going to do with this thing. Well it's made of high quality aluminium and if all the electronics are stripped out it would make a great project box. I have a high current power supply project in mind and this would make an unique case to put it in. The PCB's I will either dispose of or sell on eBay. If anyone is interested in purchasing them or the box as a whole, let me know. That will have to be quick though as I will be getting rid of it eventually. It weighs a ton and takes up space. It was bought really as a curiosity item and it was fairly cheap. If this video is a success, I may do other obscure electronics teardown videos. I just need a source of cheap and / or useless obscure crap for me to tear apart.

I managed to come across some salvaged LED display modules from a large LED display board on ebay. A little digging reveals that it originally used in cinema lobbies for displaying movie titles and showing times. I bought one to experiment with and see if it could be driven from an Arduino as I had some time on my hands with the covid19 lockdown. The main controller board was missing and there was no datasheet so I had to do some reverse engineering. The data input is via a 14 pin connector and there is another at the opposite end to daisy chain to the next module. The 7 rows are driven through a 74HC373 latch used as a buffer then to a mosfet driver IC. The 60 columns are driven by MIC5821BN high power shift registers. This is a fairly standard setup and was relatively easy to get working the only complication being that the row data logic needed to be inverted. Also the way the shift registers work is a little different to the fairly standard 74hc595 and they don't work on higher SPI speeds where the '595 will. With some sample code I was able to get the display to work and modified the code to accept new messages sent via serial and store them in eeprom. It can serve as an advertising board or adapted to display the date and time as a trendy clock for example.

In this video I demo a simple electronic load I made as I had plenty of time on my hands due to the lockdown. I am building a bench power supply at the moment and I thought a constant current load would come in handy for testing it when it's finally built. Constant current (electronic) loads are useful devices that can be used to determine the real capacity of a battery or simply for testing power supplies at certain loads. Much easier than using load resistors as I can set any current I want from 20mA to 3.5A at up to 15V. This is a simple circuit using an lm358 and a logic level MOSFET. This gets hot so a large heatsink was used, here I used an old cpu cooler. Second thing is just a damp detector I put together and finally blowing some electronic components up for the sake of it. Got a lot of crap to sell on ebay or destroy if it does not sell. For lots of projects based on the Arduino & 8051 plus other electronics related ramblings see my blog at https://www.adrian-smith31.co.uk/blog

I was given another watch cleaning machine to repair but this time it wasn't as ancient as the 1940's era machine I repaired the other month. I guess this was from the 1960's but it was still a massive electrical shock risk. Electrical safety standards did improve from the 1940's - they put a metal cover over the electrical connections and controls. That's it. As it was it still left water and cleaning chemicals to be splashed all over the exposed wiring and controls live at 230V with no earth in place. The wiring was all corroded and rotten, the motor was knackered and the heating element so rusty and corroded it just disintegrated. So to make this thing safe like the last machine I stripped it down to the bare chassis and threw everything else in the bin. I then gave it a good clean with dish soap as the cleaning chemicals left a sticky, smelly residue all over the place. Some of the paint came off when I cleaned it so I repainted the base. The second part was replace it all with low voltage 12-24V components which you can see in the video. The controls I moved to a waterproof box fitted to the front of the machine over where the old control panel was. The only exposed wiring was to the heating element but this was insulated and waterproofed later. Inside the box there's just a motor speed controller, a switch and an LED. Originally a 50 watt wirewound 2K potentiometer was used to vary the AC motor speed. I brought it into the 21st century by adding an electronic controlled speed controller although it was DC rather than AC. This video probably won't interest regular viewers but it's a demo for the guy who owns it as well. Parts used:- Motor https://www.amazon.co.uk/gp/product/B07S6L9CT6 Drain cover https://www.amazon.co.uk/gp/product/B00VITUIZO Speed controller https://www.amazon.co.uk/gp/product/B06XHGP58T PSU https://www.amazon.co.uk/gp/product/B07VQYPJW8 Connector https://www.amazon.co.uk/gp/product/B07PDXG3BT Heating element https://www.ebay.co.uk/itm/DBK-HP03-1-08-24-HEATER-PTC-F-PLATE-30W/173530709887 Box https://www.ebay.co.uk/itm/WATERPROOF-PLASTIC-ELECTRONICS-PROJECT-ENCLOSURE-CASE-COVER-JUNCTION-BOX-IP55/302502060574 Plus other misc bits I had in my drawer such as block connectors, cable and fixings.