Monday, 29 March 2010

Generating Interest

I recently acquired a Coleman Power Mate 6.5hp petrol generator that had been the victim of a flood and the owner was going to dump it, but gave it to me to play with. It's almost identical to the one in the photo. My son (4, nearly 5) enjoyed cleaning all the mud and grime off it and then we took the petrol tank off, cleaned it some more and set to work trying to get the engine to turn over. The whole engine and the dynamo was full of water, but we drained as much out as we could and then used the compressor to blow air through the engine and get the rest out. Some fresh oil and a liberal application of WD-40 into the plug hole and with a bit of rocking back and forth I got the piston free and turning over. There is some compression and a good spark, but so far no life so the next thing to do is take a look at the carburettor and make sure fuel is getting into it okay.

Saturday, 27 March 2010

Alternative Alternator

Finally got myself into gear and got the alternator out of the MR2. Unfortunately that type isn't made any more and since there are more honest MPs than there are 4A-GZE engines in the UK, I'll just have to get it rebuilt. In the process of getting the alternator out I had to take the A/C compressor off, big heavy thing it is too. I had the A/C de-gassed a few years ago intending to remove it to reduce weight, but never got round to it. I guess now is as good a time as any.

Wednesday, 24 March 2010

Psion II I/O Board

Just a quick update on the Psion II I/O board. The basic board is now finished and has 1 8-bit output and 1 8-bit input port and everything works as expected.
The next job is to add two L293D quad half-H drivers (which makes 4 full H-bridges for 4 motors) to drive the 4.5volt Lego motors.

iPaq DIY Serial Connection

I swapped a BBC Micro I had for this neat little iPaq PDA. The screen is a bit funny, but it just seems to be a problem with colour depth and on console applications isn't a problem because there are only a few colours being used. The iPaq could communicate via RS232 or USB, but this type only came with the USB cradle. A bit of research and I found the Kronos website, authors of the excellent Zeus programming environment and purveyors of fine information about iPaq connections. I was able to make up this custom connector from a broken car power adaptor which has both RS232 and power connections. The soldering was very fiddly and I used a fair bit of heat-shrink tubing to make everything neat, but it looks and works great. Now if I can get an OBD II to RS-232 interface cable, I can have real-time vehicle diagnostics on the cheap.

Thursday, 18 March 2010

Turbo spin down

It was the turbo on the old Scenic RX4 (a common problem apparently due to oil starvation) and it nearly blew up just as my wife got to the garage. It's going to cost a lot to put right unfortunately, so not a great day.

On the plus side I acquired a petrol generator that needs a little TLC after getting soaked in a winter flood. A bit of a strip down, a good clean and some WD40 and hopefully we'll get it back to life.

More of the buggy.

Monday, 8 March 2010

Laptop Guts

These are the innards from an old Pentium I laptop, maybe a Dell, I can't quite remember. Anyway the screen wasn't working properly so that was dumped and the BIOS set to switch to the VGA output by default and now we have a motherboard that will run on a single 12-volt supply (the red and black wires in the photo). Laptop batteries tend to be anything between 10 and 15 volts, but since the computers all have power management circuitry I've never met one yet that wouldn't run happily on a smooth 12 volt supply.

The hard drive is in fact a 16Mbyte Compact Flash card connected using a 99p converter bought on eBay. CF cards have an IDE-type interface so they are ideal as solid-state drives. The only drawback is the relatively low number of writes they can handle before they burn out. Fine in a camera, not so fine in a PC running an OS with a swap file. Ideal if using FreeDOS or Linux from a ramdrive though. In these cases you can even write-protect the CF card in some situations and it will have an almost limitless lifespan.

The VGA output could be taken via the VGA-Video converter to one of my little 7-inch displays (see earlier posts).

Sunday, 7 March 2010

Web Site

Just playing with Serif WebPlus, an HTML-based web design program. Not as sophisticated as Dreamweaver and definitely not as flash as using PHP (I am not worthy), but good for quick web design jobs with minimal fuss.

I spent some of my weekend trying to sort out my wife's car, a 2003 Renault Scenic RX4 1.9dCi. The RX4 is an odd hybrid, a 4-wheel drive spacebus, which came along before any marketing guru thought up the concept of a 'crossover,' which seems to be a 2-wheel drive car masquerading as a 4x4.

Anyway the EGR valve was clogged up and un-clogging it has made starting the car a breeze, but there is a deeper problem causing power loss and white smoke above 2000 rpm. I've narrowed this down to a turbo or MAF sensor issue, hopefully the latter...

Alternative Energy

This is an old photo from 18 months ago when I carried out a few experiments with solar water heating. The Centre for Alternative Energy in Wales publish a great book on DIY solar water heating and one design uses these Stelrad-type radiators. You need ones with 4 inlet ports (one at each corner) so that you can arrange diagonal flow and then you need to paint the radiator matt black so it will become an efficient collector because white just reflects the sunlight away.

The experiments were pretty successful and on a hot day the water in the radiator rose to over 60 degrees Celsius without any insulation. That's the problem unfortunately. This collector is about 2sqm which is about a quarter of what would be needed and boxed up it would weigh too much to be mounted safely on a roof.

Anyway, this summer I'm going back to this idea, but I'm going to build a double collector using the other method from the CAE booklet, which is a copper pipe and vane design and will be less than half the weight.