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Author: The Engineer
Site Hosting
There have been quite a few updates to the hosting solution for this site, which is hosted locally in my house, from the above setup, in a small comms rack, to a new 22U half rack, with some hardware upgrades to come.
Core switch here has been removed, with the rest of the core network equipment. The site was kept online by a direct connection into the gateway to the intertubes.
New 22U rack, with the core switch, FC switch & management & monitoring server installed.
As I had no rack rails to start with, the servers were placed on the top of the rack to start off, here is the Dell PowerEdge 860 pfSense core router installed, with the initial switch wiring to get the internal core network back online. This machine load balances two connections for an aggregated bandwidth of 140MB/s downstream & 15MB/s upstream.
The tower server behind is the NAS unit that runs the backups of the main & auxiliary webservers.
Still with no rack kits, all the servers are placed on top of the rack, before final installation. This allows running of the network before the rest of the equipment was installed.
The main server & aux server are HP ProLiant DL380 G3 servers, with redundant network connections.
Still to arrive are the final rack kits for the servers & a set of HP BL20p Blade servers, which will be running the sites in the future.
Stay tuned for more updates as they happen!
IBM Ultrastar Failure
Here is a SCSI U320 Ultrastar drive with a slight issue: the magnetic coating has been scrubbed off the substrate. I’ve never seen this happen to any other drive before.
The inside of the drive is coated with the resulting dust created from this rather epic failure mode.
Brightwell Brightstar II BSL4 Dosing System
Here is an old chemical dosing system for industrial washing machines. These units are 4-pump models, with dual pumpheads. The motors are reversed to operate alternate pumps in the same head.
From 2006, this is a fairly old unit, and made in the UK.
Main controller PCB, with interface to the power electronics via the ribbon cable, an external serial port for programming to it’s left. Powered by an ST microcontroller. The LCD is below this board.
Main power supply, sense input & motor driver boards. The PSU outputs +5v, +12v & +24v. The inputs on the lower left connect to the washing machine & trigger the pumps via the programming on the CPU. The motors are driven by L6202 H-Bridge drivers from ST.
Motor & gearbox assembly on the back of the pumphead. These are 24v DC units with 80RPM gearboxes.
UPDATE:
As it seems to be difficult to find, here is the user manual for this unit:
[download id=”5557″]
Routemaster Control Unit
This is the control unit for a Routemaster system, that downloads traffic information for the area local to the vehicle.
Here is an overview of the unit, in it’s aluminium box.
Here is the unit with the top cover removed, showing the pair of PCBs. The bottom PCB is the main control PCB, the top one holds an IC similar to a SIM card & part of the radio.
Here is the main PCB removed from the casing, contains the program ROM & microcontroller. for the system
Daughtercard view. This holds another programmed CPLD, the custom SIM-like IC & the RTC battery, along with some power conversion circuitry.
This is the radio receiver, looks to be AM, the large loop antenna can be seen at the bottom of the box.
Media PC Build Log
This will be the record of building a new Media PC, above you can see the finished system.
It’s Mini-ITX based, with on-board HDMI output, specifically to run XBMC via Fedora for media purposes.
This is the case that is being used, around the size of a Shuttle PC. It has a single 3.5″ & 5 1/4″ bay, for a HDD & ODD, front panel USB, Firewire & Audio.
Motherboard to fit the case. Supports Intel Core i5 series CPUs, with up to 8GB of DDR3 RAM.
Other features are on-board full surround audio, HDMI, eSATA, & a single 16x PCIe slot.
Matching memory for the motherboard, a pair of 4GB DDR3 units.
Having never been impressed by bundled coolers with CPUs, here is an aftermarket low-profile unit, with solid copper core for enhanced cooling. This cooler is specially designed for Mini-ITX uses.
The brains of the operation, Core i5 650 CPU, should handle HD video well.
New Feature – Geiger Counter
Here’s something new, an internet connected Geiger counter! The graph in the sidebar is updated once every 60 seconds, and can be clicked on for a larger version. Measurements are in Counts Per Minute, the graph logs 1 hour of data.
The counter itself is a Sparkfun Geiger counter, with the end cap removed from the tube so it can also detect alpha radiation.
Connected through USB, a Perl script queries the emulated serial port for the random 1 or 0 outputted by the counter when it detects a particle. The graph is pretty basic, but it gets the point across. Anybody who wishes to contribute to improve the graphing is welcome to comment!
Update!
Well things have been hectic over the past couple of months.
With a new job & a new addition to the family I’m not getting much time to update the site, however there are a few things on the way!
More Raspberry Pi stuff will be arriving soon, running the GPIO with a web interface.
I found a fault with Dell servers that I’ve managed to fix without having to replace some very expensive parts! This might be of interest to people with such servers, more info to come soon!
Ultracapacitor Voltage Regulation
As an ultracapacitor has a pretty linear discharge curve, some electronics are required to make them behave more like batteries, such as as SEPIC converter.
On the right is a MuRata Power Solutions UQQ-12/8-Q12P-C switching regulator, which will accept a 9-36v input source & output a constant 12v at 8A (96W).
Raspberry Pi GPIO Experiment Board Improvements
Here are the first set of mods & improvements to the RasPi Experiment board. Instead of the solder-point experiment space, I have added a standard mini-breadboard, even though it’s a little too long to fit on the board properly.
In the DIP breakout, is a MAX232 TTL-RS232 interface IC, useful for interfacing directly to the Pi’s UART, made available on the GPIO breakout. I will be hardwiring the MAX232 IC into the GPIO port, & fitting headers to the relevant pins on the IC breakout to make interfacing to the Pi easier.
All the MAX232 requires to operate are a 5v supply & 4 1µF capacitors.
The new TO220 device next to the breadboard is a TIP121 darlington power transistor.This is rated at 80v 5A continuous. Useful for driving large loads from a GPIO output.
More to come soon!
Raspberry Pi GPIO Breakout
After seeing these on eBay for £8.99 I thought it might be a good deal – interfacing with the RasPi’s GPIO & it has built in power supplies.
As a kit, it was very easy to assemble, the PCB quality is high, and is a fairly good design. It worked first time, the regulators hold the rails at the right voltages.
However there are some issues with this board that bug me.
The documentation for the kit is *AWFUL*. No mention of the regulators on the parts list & which goes where – I had to carefully examine the schematics to find out those details.
The 4x 1N1007 diodes required weren’t even included in the kit! Luckily I had some 1N4148 high speed diodes lying around & even though they’re rated for 200mA continuous rather than the specified part’s 1A rating, the lack of heatsinking on the regulators wouldn’t allow use anywhere near 1A, so this isn’t much of a problem.
Component numbering on the silkscreen isn’t consistent – it jumps from R3 straight to R6! These issues could be slightly confusing for the novice builder, and considering the demographic of the RasPi, could be seen as big issues.
On the far left of the board are the 5v & 3.3v regulators, well placed on the edge of the board in case a heatsink may be required in the future. However the LM317 adjustable regulator is stuck right in the middle of the PCB – no chance of being able to fit a heatsink, & the device itself seems incredibly cheap – the heatsink tab on the back of the TO-220 is the thinnest I have ever seen. Not the usual 2-3mm thick copper of the 5v & 3.3v parts – but barely more than a mm thick, so it’s not going to be able to cope with much power dissipation without overheating quickly.
As the adjustable rail can go between ~2.5v – 10v, at the low end of the range the power dissipation is going to shoot through the roof.
The GPIO connector – this could have been done the other way, at the moment the ribbon cable has to be twisted to get both the Pi & the GPIO board the same way up. Just a slight fail there. See the image below
The power rails are not isolated out of the box – there is no connection between the 5v & 3.3v rails & the Pi’s GPIO, but the GND connections are linked together on the board.
Getting the ribbon cable through the hole in the ModMyPi case was a bit of a faff – the connector is too big! I had to squeeze the connector through at a 45° angle. The case is also remarkably tight around the connector once it’s fitted to the board – clearly the designers of the case didn’t test the an IDC connector in the case before making them!
Everything does fit though, after a little modification.
Here is the unit all built up with the case. The top cover just about fits with the IDC connector on the GPIO header.
More to come once I get some time to do some interfacing!
2600 Farad Ultra Capacitors
Just a quickie to note down the current progress of another project – Ultracapacitors.
Pictured right is a bank of 6 2.5v 2600F Maxwell Boostcaps, for a total of 15v at 433.333F. A total energy storage of 48.7kJ.
Coming soon will be the inclusion of charge balancing, using Zener diodes & integrating a DC-DC converter on the output to hold the bank voltage at 12v when being used.
Vintage Optical Block
I thought this would be of interest, as it’s from a drive circa 2001, (DVD-CD-RW).
It’s the biggest & most complex optical block I’ve ever seen, with totally separate beam paths for the IR CD beam & the visible DVD beam. It also combines the use of bare laser diodes & combined diode/photodiode array modules for the pickup.
Here’s a look at the optics inside the sled, on the left is a bare laser diode & photodiode array, for the CD reading, and the bottom right has the DVD combined LD/PD array module. The beam from the CD diode has to pass though some very complex beam forming optics & a prism to fold it round to the final turning mirror to the objective lens at top center.
There are also two separate photodiodes which are picking up the waste beam from the prisms, most likely for power control.
OMXPlayer Series Play
This is a little script to make OMXPlayer on the Raspberry Pi cycle through every file in a specified folder, useful for playing sequential movies or series of episodes.
#!/bin/bash if [ x"$1" = x"help" -o x"$1" = x"--help" -o x"$1" = x"-help" ];then echo "Usage: omxseries [folder path]" echo "Audio Mode can be either 'hdmi' or 'local'." echo "Folder Path is the full path to the video files on your system." echo "This script will attempt to play every file in the target folder, with any file extension," echo "so ensure that only valid video files are present in the target folder to avoid errors." exit fi
for file in $2/* do omxplayer -o $1 $file done
Example:
[root@raspbian ~]# omxseries hdmi /media/stuff/videos
would play everything in /media/stuff/videos and send the audio over the HDMI port.
Download the script to your Pi with this code:
wget -O /usr/bin/playseries http://www.experimental-engineering.co.uk/wp-content/plugins/download-monitor/download.php?id=1 && chmod +x /usr/bin/playseries
ModMyPi Raspberry Pi Case
Finally, some protection for my Raspberry Pi! The PCB fit is slightly loose, but that was quickly sorted with the application of a couple of spots of hot glue in the corners.
Unfortunately, the case is a couple of mm too small to fit the main board from the Pico Projector inside, so I won’t be butchering that into the case with the Pi as yet. What is required is an interface to the display engine from the Pi’s DSI interface.
The pi all boxed. up. The only thing that this case would now require is a lightpipe to direct the LED’s light to the openings in the case, as they are very difficult to see at present.
AutoFace HID Ballast & Bulb
I bought one of these cheap HID kits from eBay to build a high-brightness work light that I could run from my central 12v supply.
At £14.99 I certainly wasn’t expecting anything more than the usual cheap Chinese construction. And that’s definitely what I got 😀
The casing is screwed together with the cheapest of screws, with heads that are deformed enough to present a problem with removal.
As can be seen here, the inside of the unit is potted in rubber compound, mostly to provide moisture resistance, as these are for automotive use.
The ballast generates a 23kV pulse to strike the arc in the bulb, then supplies a steady 85v AC at 3A, 400Hz to maintain the discharge.
This module could quite easily be depotted as the silicone material used is fairly soft & can be removed with a pointed tool.
Here is the bulb removed from it’s mount. Under the bulb itself is a solenoid, which tilts the bulb by a few degrees, presumably to provide dim/dip operation for a headlight. This functionality is superfluous to my requirements.
Closeup of the arc chamber of the bulb.
MicroVision ShowWX+ HDMI Laser Pico Projector
Here’s the teardown of the projector itself! On the right is the info label from the projector, which covers the flex ribbon to the VGA/composite input board below.
This unit is held together with Allen screws, but is easy to get apart.
Here’s the insides of the projector, with just the top cover removed. The main board can be seen under the shielding can, the Micro HDMI connector is on the left & the MicroUSB connection is on the right. The USB connection is solely for charging the battery & provides no data interface to the unit.
On top of the main board is the shield can covering the PicoP Display Engine driver board, this shield was soldered on so no peek inside unfortunately!
The laser module itself is in the front of the unit, the laser assemblies are closest to the camera, on the left is the Direct Doubled Green module, in the centre is the blue diode, and the red diode on the right. Inside the module itself is an arrangement of mirrors & beamsplitters, used to combine the RGB beams from the lasers into a single beam to create any colour in the spectrum.
Here is the module innards revealed, the laser mounts are at the top of the screen, the green module is still mounted on the base casting.
The three dichroic mirrors in the frame do the beam combining, which is then bounced onto the mirror on the far left of the frame, down below the MEMs. From there a final mirror directs the light onto the MEMs scanning mirror before it leaves through the output window.
A trio of photodiodes caters for beam brightness control & colour control, these are located behind the last dichroic turning mirror in the centre of the picture.
This is inside the green laser module, showing the complexity of the device. This laser module is about the size of a UK 5p coin!
And here on the left is the module components labelled.
Here is the main PCB, with the unit’s main ARM CPU on the right, manufactured by ST.
User buttons are along the sides.
Other side of the main board, with ICs that handle video input from the HDMI connector, battery charging via the USB port & various other management.
ShowWX+ Pico Projector First Light
Above is the image projected from the Pi, on the default login screen. Distance from the projector is approx 10 feet.
State of the art projector mount, fashioned from several cable ties. HDMI cable is plugged into the right hand side of the projector.
Unfortunately the projector cannot handle audio on the HDMI connector, the 3.5mm headphone jack on the projector is for splitting audio out of the iDevice connection only, and does not make the HDMI audio stream available.
The Raspberry Pi, hosting a USB keyboard, & USB powered speakers. Running the standard Debian release, on a 16GB card, with omxplayer installed for media functions.
Cisco 2G Fibre Channel SFP Module
Here is a 2Gbit Fibre Channel transceiver from Cisco Systems in SFP module format.
Here the shield has been removed from the bottom of the module (it just clips off). The bottom of the PCB can be seen, with the copper interface on the left & the rubber boots over the photodiode & 850 nm laser on the right.
Here the PCB has been completely removed from the frame, the fibre ends slide into the rubber tubes on the right.
Top of the PCB, showing the chipset. There are a pair of adjustment pots under some glue, next to the chipset, presumably for adjusting laser power & receive sensitivity. The laser diode & photodiode are inside the soldered cans on the right hand side of the board, with the optics required to couple the 850nm near-IR light into the fibre.
The Perfect Companion To The Raspberry Pi
As I’m building a portable “media center” with my first Pi, I was looking for a suitable screen. I remembered the existence of these:
A laser pico projector combined with a Pi, in a small enough package would make a fantastic
little portable media player. So £220 was shelled out 🙂
Along with the case for my Pi coming from Mod My Pi, I am aiming for a device as small as possible. At some point I will fit the Pi into the same package as the projector, if it can be cannibalised in such a way 🙂
Check back for an update with running images of the projector, powered from the Pi’s HDMI output.
I will also be doing the standard teardown of the projector when time allows 🙂
Bootnote:
Micro HDMI Connections: These are CRAP. They don’t stand up to any form of day-to-day use, and the projector began displaying a blue screen with “INVALID VIDEO MODE” as soon as anything was plugged into the Micro HDMI port. A quick attack with a jeweller’s screwdriver fixed the port, as it had become loose.
RasPi Terminal Customisations
As seen in the previous post, the SSH terminal of my Pi gives some useful stats. This is done using GNU Screen, with a custom config file.
This file is .screenrc in your user’s home folder. My personal code is posted below:
~/.screenrc
startup_message off
backtick 1 30 30 $HOME/bin/disk.sh
backtick 2 30 30 $HOME/bin/mem.sh
hardstatus alwayslastline
hardstatus string '%{gk}[ %{G}%H %{g}][Disk: %1` RAM: %2`M][%= %{wk}%?%-Lw%?%{=b kR}(%{W}%n*%f %t%?(%u)%?%{=b kR})%{= kw}%?%+Lw%?%?%= %{g}][%{Y}%l%{g}]%{=b C}[ %m/%d %c ]%{W}'
nonblock 1
defnonblock 1
I have uploaded the pair of scripts for the backticks, and they can be found here:
More to come once my new 16GB Class 10 SD Card arrives!
The Pi Has Arrived!
Finally, the Pi has arrived! Currently running the Debian release on a 2GB SD, with some minor modifications.
SSH terminal, running a screen session with a custom status bar.
More updates to come!
Raspberry Pi Update
Well I got my delivery info finally, the week commencing 28/05/2012. Experiments to come once I have it!
Coming Soon – Raspberry Pi
Coming soon! Unboxing of the Raspberry Pi & first experiments! Estimated start of June!
LED Lighting Project: Part 2
Following shipment of another 25x 3W LED modules, the project is restarting.
More details of the power & cooling systems will be posted soon!
More as it happens!
