Tuesday, 27 December 2011

Homebrew 7" Touch Screen

(Touch monitor under test using Linux Mint)

I've posted a short set of photos of the LCD monitor conversion so far.


The monitor is one of a pair purchased on eBay for £15 (s0 say £8 per monitor) and the touch panel cost £14 again from an eBay store in the far east. Total cost is under £30 and a lot of fun in the research and modification.

The monitor is not VGA, but the picture is remarkably sharp and with big icons (such as Linpus or Tiny Core at 400 x 300 or something) this would be ideal as an in-vehicle dash control panel.

I've just ordered some panels (just the panels for now) for under £5 a panel. Now the electronics are the more expensive part, but I'm about to start looking at reading these resistive panels directly from a micro controller using A/D conversion.

More on that in the New Year.

Thursday, 15 December 2011


I thought this was pretty clever when I spotted it a while back passing a farm on the coast. They've put a row of solar water panels on an outbuilding roof. Nice south-facing roof too and low enough to make installation and maintenance a breeze. The only wonder is how the water is being piped from the outbuilding to the main house (if it even is). There's a fair loss in heat over even short distances which is why it is always recommended that solar panels are placed as close to the hot water tank as possible.

Still a great installation.

Tuesday, 6 December 2011

Large 4-digit LED display board

These are 1-inch green LED 7-segment displays I picked up on eBay. I got 8 in total for a few dollars. I wanted to use up some off-cuts of stripboard so I ended up sticking 2 pieces together using epoxy glue and a strip of scrap ABS plastic which is on the back. The DIL socket will hold a MAX7219 integrated circuit when the display is finished. The MAX7219 is an intelligent driver which can handle binary-coded decimal as well as bit-addressed data. I'm going to play about with this and add it to the ever-growing box of 'modules' for the car computer project (if ever...) as it would make a great rev counter or speedometer, or both.

LCD Monitors

Internals of the 6.2" LCD monitor. Just 4 connections needed, 2 for power and 2 for the composite video signal. Power connection is marked (strangely) 7v, but the power board supplied 9v and it seems to work on anything between 6 and 12v.

Internals of the 7" LCD monitor. The lower circuit board handles power and has a stereo audio amplifier.

Monday, 21 November 2011

Covering Up

I've been looking at a quick, cheap way to make a dry store area for scrap timber, old pallets and logs. I needed somewhere out of the rain, but where there will be a breeze to encourage drying and the best space was at the gable end of the house where we have our coal bunker.

I bought this tarpaulin for about £4 from CPC and rigged it to the side of the house using 10 cup hooks (5 at the top and 5 at the bottom). The first attempt went a bit wrong because I hadn't put enough of a rake on the tarpaulin so the rain just pooled at the bottom. This adjustement seems to be working, but I think I'll drop the bottom end a few inches to make sure any rain runs off.

Thursday, 17 November 2011

Anyone for a slice of Pi?

Coming along nicely (almost segueing into) my last post, here's the same idea, 20 years later.


A tiny credit card-sized single-board computer aimed at teaching kids (and anyone else) about old-school computing, growing-your-own code and building your own kit.

What really attracts me to this one is the provision of an analogue video output, which I could hook up to one of the old 6" LCD screens I've been messing with for about 2 years. I'm thinking of a 20MHz PIC like a 16F690 to collect raw engine data down at the ECU and to send it via a long USB cable to the cabin where a Raspberry Pi running TinyCore and my own Gambas program would decode this into graphs and charts. Rather than a touch display, I'd like to revisit the old Renault Laguna stalk controls, but via another PIC (maybe a 16F628) and USB so the control buttons have some degree of 'intelligence' for the computer to interpret.

Getting closer, but oh so slowly!

Tuesday, 15 November 2011

Sunday, 9 October 2011

Life on Mars

"We're the Sweeney son and we haven't had our dinner."

(Image by Bill Walsh)

Friday, 7 October 2011

Stoved In

Short version...

Just over 2 years ago I purchased a wood-burning stove (actually multi-fuel) at a good price and we had it installed as a dry stove (i.e. no hot water). The stove actually had a back boiler, but at the time we couldn't afford the plumbing work and were quite happy to use it as a living-room fire. Now this was no pot-belly job. If you know me, you know that about once every 5 years I take the head staggers and this was a classic version (the last one was buying the MR2 sight-unseen and bringing it back from England). This stove is huge. It weighs 240kg (that's a quarter ton in old currency) and at full tilt can reach 500 degrees C inside and generate 21kW of heat, enough to run at least 10 radiators.

So 2 years passed and we had saved money from using less oil (a lot less) and thought we'd get it plumbed-in. This cost the raw part of £2k and is a beautiful piece of work, all done in copper pipe. So the plumber came to commission the whole thing and water started pouring out of the stove. Lots of water. There was a pinhole-sized hole in the back of the stove in the seam of the boiler. This being cast iron there is no simple way to repair it.

After much gnashing of teeth we decided that everything being equal it would be better to buy an identical replacement stove as we are sure we will still save money and it will pay for itself in savings on oil in 3-4 years. To give an illustration, in the last 2 years the cost of oil has risen by 30% while the cost of coal has stayed the same and the cost of wood has gotten cheaper as more people have entered the sustainable energy market.

I will keep my readership posted (all 3 of you).

Levelling Out

I bought a USB-to-Serial converter a while back to play with that had the large standard USB plug (rather than a socket). These modules have a CP2102 chip on board which uses the 3.3V standard so the only issue I had with it was a level change problem from 3.3V to the 5V I'm using with my 16-series PICs.
I turned up a very neat bi-directional solution using just one MOSFET and 2 resistors for each channel (see above). Even though the transistors are surface mount(i.e. tiny) this was easy enough to build and the USB converter now works a treat, so much so that I bought another one with a micro USB socket which I think would be more use mounted into an actual project. Not only that, but early indications seem to show that this version doesn't have a problem with the voltage level shift and is working quite contentedly with the 5V PIC circuits.I've been communicating with these units using the Gambas2 programming language under Linux. Gambas2 is similar to Visual Basic although the developers stress it is not a clone. Under Linux, opening a connection to a USB serial port is as simple as calling up 'ttyUSB0' and off you go. Try doing that in Windows!
The next step is to use the bar graph programming example in Gambas2 and modify it to lift data from the serial stream coming in from one of these modules.

(If I ever get time...)

Monday, 26 September 2011

Six Inches - Big Enough

I got around to taking the screen out of one of the LCD units to see what could be done with it. For a start the actual screen is 6.2" (according to the serial number and a ruler) not 7" as on the manufacturer's website, but that's no bad thing. It turns out a 6.2" screen is just the right size to fit in a double-DIN car radio slot, which prompts all sorts of ideas.

It also turned out that there were 2 circuit boards, a big one with an audio amplifier and some power supply circuitry and a small one for the actual screen. Essentially the screen will operate with just a 4-wire connection (9 volt, GND, Video and Video GND). There is another connector for options (screen mode, colour and brightness), but with nothing connected to this the monitor defaults to perfectly use-able settings.

In the photo I have it hooked to a PC via a VGA-to-Video adaptor. The computer is running Tiny Core Linux (my new favourite distro) in 640 x 480 mode (I think). It will go down to 320 x 240 which gives huge icons that would be great with a touch screen.

The wallpaper is Pink Floyd's 'Animals' album cover, recently re-created over Battersea Power Station - "Every Dog needs a home, a shelter from Pigs on the wing."

Tuesday, 13 September 2011

DIY Immersion Heater Control

This started life as a plug-in countdown timer I got in a clearance sale at CPC.

After taking it apart and removing the 13-amp plug and socket parts I was left with a the guts of an immersion heater timer that can be set between 5 and 50 minutes in 5-minute steps . The relay was rated for 20A at 240V so it could certainly handle the heater current, so I set about blanking off the hole where the socket was and then glued the back of the timer to a standard blanking plate with Araldite. I drilled a hole through the middle of the blanking plate, added a 3-way terminal block and voilá, an immersion timer for less than £5 to compliment my £5 central heating timer. Now there is no danger of the immersion heater being left on for more than 50 minutes and if you need hot water for washing dishes that's just one press.

Thursday, 25 August 2011

I Have The Power (Steering)

When I re-fitted the PAS pump it was deceased, kaputt, had gone to the great pump house in the sky. I got another one on eBay for £145 delivered, fitted it and all was well. Power steering for the first time in 2 months, which felt weird. The whole job cost about £250, a lot less than the £1000-plus I had heard people were paying Skoda for the same work.

The day after that the engine started acting-up, losing power under load once you were up to 30mph or so. A bit of bodging and I narrowed this down to the EGR valve, which has been temporarily put out of action until I get time to clean it out this weekend.

Off to MOT and it failed on... a leaky rear shock absorber! With all the other things I'd forgotten to check them. Critical mistake becuase with a clean and rub down it might have passed as the leak isn't too bad yet, more of a smear. Anyway I got a second-hand shock for £10 up at Traynor's in Malusk so that's Saturday taken care of.

Good thing is I have an excuse to drive the MR2 for a few days until I get the Skoda re-tested.

UPDATE - Replacement shock is now fitted; a 45 minute job including cleaning everything under the wheel arch such as the brake pipes and hosing out the plastic liner which had 10 years worth of crud under it!

ANOTHER UPDATE - The problem with the engine came back after 2 days, but when I took the EGR valve off again it was clogged with even more soot. I gave it another really good clean and used a piece of broomhandle to push it open and closed a few times while painting Gunk in round it. The following morning the car ran like a pig for 5 miles and finally stalled, but then suddenly burst into life and has been fine since. My guess is that I need to clean this thing regularly now the engine is getting on a bit.

Monday, 18 July 2011

PAS Pump

Power steering hydraulic fluid leaking out of the end of the steering rack (with the gaiter off showing track rod joint)

Power steering pump back in place.

Sunday, 10 July 2011

Let there be light...

Probably one of the best things I've been (kindly) given on Freecycle is an old flourescent light fitting which I use when I'm working under a car. Combined with the inspection light it means I can actually see what I'm doing without being blinded.

This is also the proof that while I'm not the fastest worker, I'm not a 'keyboard mechanic' - if I say I've done it, I've done it, warts and all.

Skoda Fabia PAS problems

The Skoda Fabia is apparently renowned for developing power steering problems and mine sprung a leak in the steering rack about a month ago. I'm going to replace the rack with one from a scrap car, but decided to clean up the pump in the process. I'm also going to replace the anti-roll bar bushings (I bought the bushings about a year ago and never fitted them) because both jobs involve dropping the front subframe.

Of course one of the track rod ends couldn't be easily removed and I needed to resort to the trusty nut-splitter and now one of the ARB drop links is up to the same trick. I've sprayed easing oil round it, but the problem with both these parts is that you need to use an Allen key to keep them from moving while you undo the bolt and after 10 years in a car that can be almost impossible.

This is the power steering pump removed from the car. As can be seen, the plastic cover and foam jacket have pretty much disintegrated. The foam was soaking and was the cause of the corrosion on the pump housing. This apparently was to reduce vibration and noise, but in later cars was abandoned. You can see why.

With the bracket removed I was able to give the housing a bit of a wire brush and a coating with a waterproofing spray. Hopefully the pump is okay because it is an expensive thing to replace although an easy enough job to do. The biggest headache is that when it is in the car the access to the green filler is only possible with the battery and tray completely removed.

I'm seriously tempted to modify this thing to put a remote filler pipe onto it that could be fed up into the engine bay and capped off carefully. I have some 10mm plastic hose and fittings kicking around and it would be easy enough to epoxy a pipe into the side of the plastic reservoir.

Sunday, 22 May 2011

MR2 App

This is my first attempt at a possible diagnostics app for the MR2, written using Google App Inventor. Unfortunately, I'm hitting a brick wall with this because the tablet is only running Android 1.6, which doesn't have a proper Bluetooth stack. App Inventor has Bluetooth coming out its ears, but can only target Android 2.o and above. I have tried playing with the Bluetooth backport to 1.6, but it won't work on this tablet. I've also scoured the 'Net to see if there is any way to run Android 2.0, but with only 128MByte of RAM this would be unlikely and very slow if I could find a build.

I'm holding out for a similar tablet at around £50 running Android 2.2 which should handle the Bluetooth with less trouble, if any.

Meanwhile the prototype diagnostics sender is coming along in dribs and drabs. I have an op-amp interface for the oxygen sensor and an RPM interface converting IG pulses to a linear voltage, not as elegant as counting the pulses, but a lot less hassle. The rest of the sensors kick out a signal in the 0-5v range so shouldn't need much pre-processing. The Bluetooth adaptor sends the data for 8 sensors out in formatted text (ASCII) once a second.

Friday, 13 May 2011

Terry Lean

My brother got me an Airfix kit of a MK1 Ford Escort for my birthday and here is the driver all painted up like a 1973 middle manager working at a soft drinks company in Sheffield. Yes, I've given him a complete back story. His suit is tailored in ICI Terylene (TM) and shoes in pleather.

Nice LED array

This LED array came out of an old Sky+ box (you know the one, it's used in all the Sky advertising). The LEDs are multiplexed, but if you only want to have one on at a time it is easy to drive them directly from an 8-bit port on a PIC. I rigged it up to a PIC 16F690 set up for analogue reading so the LEDs work like a neat little meter with the green arrow at the mid-point. I'm thinking of using this as fuel/air meter.

Thursday, 28 April 2011

Tablet Internal Bluetooth

When I had the tablet PC apart I noticed that the camera had just 4 wires coming out of it, so it was probably USB. A bit of investigation showed the three USB connections (camera, internal wi-fi and the USB socket) all going back to one chip on the board, clearly a USB hub of some sort.

Anyway, the camera was a bit pants and I thought it would be much cooler to have internal Bluetooth, especially now I am playing about with the Google App Inventor's Bluetooth functions.

I disassembled a USB Bluetooth adaptor and made a test connection to try it out in place of the camera. First time out it didn't work, but reversing the D+ and D- USB connections did the trick and it worked. For some odd reason the camera module had these connections reversed although every other USB module I've seen including the wi-fi one in the tablet seems to follow the standard USB wiring conventions.

All I need to do now is tidy the wiring up by removing the USB plug from the Bluetooth module and soldering the wires directly to the board and then spot glue it into the case where the camera was.

In the photo above, the wi-fi is the module smack in the middle and my Bluetooth adaption is the one on the left sitting upright on top of the battery compartment.

Friday, 22 April 2011


DOS running 'live' on a netbook. I upgraded the RAM on this original Acer A110 from 512Mb to 1Gb using a RAM module I got from another kind donor and am waiting on parts from China to do a cheapo upgrade of the 8Gb solid-state HDD to an 80Gb SATA one extracted from a laptop that had been run over by a car (I kid thee not, actually run over... by a car). Anyway in the meantime I've been trying different Linux distros, Android and even DOS on it and DOS is actually pretty cool, especially FreeDOS and FreeGEM.

Taking the tablet! - WORKING

I bought this Android tablet from a mate for £20. I think it was a warranty return or something he got on eBay. Anyway, it worked for about a week and then just quit and it looks like the power board or maybe the inverter for the screen has gone wonky because there is a buzzing sound when you try and power it up. That said, after just a week I was hooked! I was able to plug a 3G dongle in and surf the web from anywhere, just like rich people do with iPads (!) and Bluetooth worked out-of-the-box with a £1 dongle from... PoundWorld. What really got me excited was when I got my first app working on it. Okay so it was only the tutorial app from Google App Inventor and admittedly it was just a photo of a cat that purred when you touched it, but it worked. Now App Inventor includes libraries for Bluetooth and USB communications so if I could get this thing working again it would be the dashboard car console to kill for, for £20!

UPDATE - THE TABLET IS WORKING AGAIN!!! I took it apart on 24/04/11 and made sure all the connectors were sound and it booted up again. Then I turned the camera round (it was upside down for some reason) and have fixed the speakers, which also didn't work.

Sunday, 6 March 2011

Touching the pad

An interesting little 'quick' project. The touchpad out of a broken laptop wired to an old PS/2 connection from an old mouse. Plug-and-play touchpad for the carputer project. Both mouse buttons work as well as the tap-to-click feature. I could mount this on the dash or pretty much anywhere. Result!

Wednesday, 9 February 2011

Kicking Myself

I finally gave up on the XDA and stripped it for spare parts as the main connector was broken. I've been holding out in the hopes I'd get a similar 'phone somewhere with a cracked screen (I narrowly missed one on its way to the dump). It just dawned on me that with the Bluetooth adaptor for communications all I needed to do was get power into the XDA and I'd have had a very useful pocket computer. Of course at the time I wasn't even aware you could send serial data via Bluetooth so I guess I have to put it down to the learning curve, but it's still annoying.

Tuesday, 1 February 2011

Weebly Web

I've been mucking around on the web again.

Check this out and send me any photos of hair salons if you see any good names.

Krazy Kutts

Weebly is a fantastic online web design system which is free for basic use (which is actually far from basic). You can add video, audio and all sorts of other things just by linking to your YouTube or podcast account elsewhere.

Wednesday, 26 January 2011


I purchased this little Bluetooth module on eBay, another special all the way from China. It cost about £7 (delivered), but in bulk they can be bought for as little as £2. The module converts a TTL serial port such as the TX/RX pair on a PIC microcontroller to a basic Bluetooth communications link.

As long as it is paired with a computer, 'phone or PDA which supports 'Serial over Bluetooth,' a virtual serial port can be set up to allow any terminal program (or DIY software) to communicate wirelessly with the microcontroller.

I got it tested last night using the basic 8-channel ADC program on the PIC 16F690, which outputs a stream of analogue values serially, usually via RS232. Anyway, after a bit of fiddling with the settings I got a test serial program written in Pocket Zeus working on the iPaq and a stream of data arrived wirelessly via the iPaq Bluetooth.

Incredibly cool and lots of application, but starting with sending engine data via Bluetooth to the dashboard. Probably taken for granted in 2011, but something unusual in a 1988 sports car.