Crystal Radio Set

Crystal Radio set using razor blade and pencil
Crystal Radio set using razor blade and pencil

These things are somewhat amazing. With nothing more than a coil of wire, a pencil, razor blade and some random wire it’s possible to construct a crystal radio set. These things are so simple the fact they work at all is like magic.

All it takes is a long piece of wire for an antenna, a ground connection and then some sort of semi-conducting material for a cat’s whisker and you’ve got a radio. ‘Semiconductor’ sounds a bit high tech, so replace that with ‘something that mostly conducts electricity, but not that well’. The signals are incredibly weak and tuning is an artform and watch where your hands go or you’ll end up becoming part of the radio!

I built the set from random junk in my house. The purple wire I have on a spool for just such occasions, the razorblade came from my bathroom (no, I’m not Emo 😉 ) as did the toilet roll tube. The cork block is actually a sanding block out my toolbox.

The ‘set’ is connected to my PC’s soundcard to amplify the signals but even with that I had to turn the volume of my PC right up to the point the speakers were humming with all the stray EM noise my house generates (the washing machine is on at the moment which can’t help things).

Crystal Radio set connected to my PC
Crystal Radio set connected to my PC

I worked out the construction of the radio by looking at a few pictures on the web and then fiddling until things worked. I had problems with the lacquer coating on the thin wire I took from an old hard drive’s read arm assembly. Eventually after some faffing and prodding I had the pencil causing giant bursts of static when it touched the razor blade. The razor blade needs to be “blue”, to do that it needs heating in a flame until it glows red.

And then the coolest thing ever happened… I picked up a football match. I hate football, it bores me to death, but the fact it came from a bunch of crap on my desk was pure magic 🙂

If you try to build one of these but it doesn’t work, test all the contacts by prodding them with your fingers. There should be little bursts of static or other noise if you touch stuff. The set is highly sensitive to everything, so if it works sit still and try not to wave your hands about. Seriously, for reasons beyond my understanding I had an excellent signal if I touched my finger to the blue thumbtack, and put a dirty spoon across the wires going to the soundcard plug. Blowing onto the pencil helped too since the contact needs to be “just right” and is utterly random.

Linux on your oven – or why fans are good in computers

Intel Celeron CPU with not enough CPU paste
Intel Celeron CPU with not enough CPU paste

So, my MAME cabinet was having stability problems all day. Either it was locking up, the network kept dropping or bits of it stopped working (like the sound). By a process of elimination I managed to make it consistently crash running Memtest86 after about ten seconds. No errors were printed about the RAM, and it did it with both sticks of RAM in the machine.

The BIOS reported the CPU at a toasty 70c which is kind of high, but then my P4 based server upstairs runs at 60, and seems quite fine with that. All the same I went to Maplin, bought some heat transfer goop and gave the CPU and heatsink a good clean. Not that the CPU needed much cleaning, since there was barely any heat paste on it. There was a large chunk of crusty, dry paste on the back of the heatsink too. Lm-sensors now reports the machine running at 40c while under heavy load.

Don’t buy cheap hole saws and expect them to last for more than one use. Also watch out, MDF is really easy to start smouldering. Make sure all the clumps of burning MDF dust are removed and the holes aren’t smoking either.

Today has been a slow, frustrating day. I “lost” four hours earlier just faffing with the machine trying to make it work. I still don’t know why the PC says the BIOS checksum is incorrect every time the power is removed, the motherboard battery is good so all I can think is the flash in the BIOS chip is starting to fail. It wouldn’t surprise me, I did get this motherboard free inside a junk PC case on Freecycle.

Mame Cabinet – With added electroshock therapy

danger-electric-shock-risk-signAs part of my ongoing “learning by my near fatal mistakes” attitude to life I’ve discovered some interesting problems with my MAME cab. While undergoing the torture known as “getting MAME to work” I found the PC kept crashing, or being just plain weird. Having to reset the BIOS every time it was powered up was getting tedious too.

So, deciding the motherboard was probably to blame I reached my hand in and went to switch it off. While doing this I noticed that whenever I touched the PSU and rubbed my finger over it I felt a strange ‘fuzzy’ bumpy sensation, exactly like the weird vibration aluminium macbook owners sometimes experience. It also caused something to emit a familiar 50Hz humming sound.

After I’d finished playing with this amusement (really, if I’d discovered radioactivity, I’d be dead by now… oooh look at the glowing warm rocks!) I set about finding the source of the faulty ground connection. It didn’t take long, the 4-way power strip I was using had faulty connections where sometimes the earth pin of the plugs going into it didn’t make a good contact with anything.

That’s all fixed now, but the PC keeps crashing so I have no idea what’s wrong. I’ll try removing the wireless ethernet card now, maybe that’s at fault.

MAME Cabinet – Part 4

Installation of the monitor inside my MAME Cocktail Cabinet
Installation of the monitor inside my MAME Cocktail Cabinet

The monitor hole has been cut, and after a lot of faffing and dropping of the monitor I have it in the correct place on a support. This was difficult enough with a TFT display, doing it with a 19″ CRT that I was originally going to use would have been really hard. It would have also made the cabinet larger, and it’s already quite big as it is.

The lid and rest of the cab are outside while a second coat of black gloss is drying and collecting flies. By tomorrow evening it should be dry enough to sand down and apply a final coat of gloss.

I spent some time last night wiring up the buttons and have now come to the conclusion cabinet wiring was probably a job given to trainee or work experience people back when cabinets were popular. It’s quite easy, it’s vaguely satisfying doing a neat job, but it’s quite tedious and repetitive.

I recompiled AdvanceMAME this morning after noticing it wasn’t playing sound. I’d forgotten to install ALSA and so the configure tool hadn’t picked this up, producing a totally silent MAME build.

Mame Cabinet – Part 3

I see a white MAME cab and I want to paint it black…

I spent some of today painting the MAME cab with black gloss paint which had the consistency of tar. Tomorrow I’ll give it a light sanding to remove the bubbles and dead flies and apply another coat. I’ll then add a final coat on Monday after cleaning the house and laying down a sheet. The final coat will be done indoors to prevent things blowing onto it. Three coats of black gloss paint should be enough to protect against chips and wear.

I also need to cut the lid and work out where the monitor needs to go. This bare wood also needs priming and painting.

After all the painting is complete I just have the relaxing job of wiring it up.

MAME Cocktail Cabinet – Continued

Finished MAME control panel for my MAME cocktail cabinet
Finished MAME control panel for my MAME cocktail cabinet

Over the Easter weekend I’ve been continuing with the construction of my MAME cocktail cabinet. The main cabinet is now complete and has been painted with MDF primer and undercoat, ready for the top coats of black gloss paint.

The controller is finished, you can see the top part in the image. I’m going for a fairly traditional stick and six buttons configuration for each player.

One of the things that has been causing me issues it the orientation of the monitor. Originally I was going to have it vertically mounted for playing shooter games, but with two sticks now on one side that doesn’t make a lot of sense. Also the software I am using – AdvanceMAME – tries to be very accurate with the video output, meaning it doesn’t smash games to fit your screen fully. On a vertically mounted screen Robotron looks awful, and on a horizontally mounted screen Galaga looks equally bad.

I think I will attach a single controller and three buttons to one short end of the cabinet, making them poke out the side like old cocktail cabinets used to. This can then be used for horizontal games.

More updates to come later in the week when I have created the lid and painted everything. I’m off to collect an old PC case from someone on Freecycle. I intend on taking out the drivebays and motherboard tray and use them to mount the PC parts in the cabinet.

MAME Cocktail Cabinet – Part 1

Part built MAME cocktail cabinet
Part built MAME cocktail cabinet

This is the first part of my MAME cocktail cabinet project. Based on plans I drew up the other week I have so far created the top and bottom sections using MDF, a substance that my circular saw eats through as if it were a hot knife running through butter.

The lid needs a hole cutting for the monitor and the top section needs attaching to the bottom section. I also need some legs from somewhere.

I’ve decided that the monitor will go in a portrait orientation, with the controls on the long side that can be seen in this picture. I was going to have the controls on both of the long ends, but then decided it would be better for two-player co-operative games if all controls were on the same side.

I am actually undecided about which way around the monitor needs to go. If I have it portrait then I can play vertical scrolling shoot-em-up games such as Galaga correctly, however then playing landscape oriented games such as Robotron and Golden Axe will be incorrect. I also need to decide what software the cabinet will run, I don’t really want to install the whole of Windows XP on the thing, I think it looks tacky. The other option is DOS if it’s still viable, or a stripped down version of Linux if I can get MAME working correctly on it. I really don’t know.

I also have no real final ideas on how the control panel should look. Right now I’m concentrating on getting the main cabinet finished, with all the edges square and smooth ready for painting. According to the Internet, painting MDF with acrylic paint works well.

MOT and MAME

My car went in for its MOT and service today, and came back at dinner complete with no problems at all. Not even a tyre or blown light. Nice and “cheap” (£40 MOT, £40 service, £5 waste disposal and £30 labour) too, unlike the £500 bill from my old car before I sold it.

I’ve also created the plans for a MAME cocktail cab that I’m going to be building. I’m hiring a van tomorrow to collect a sofa from my parents and will also use it to get the required wood. I found the free copy of Draft It fairly straight forward to use. Took me three revisions of the drawings to get the correct one, with me having a small issue transposing two numbers in a key measurement and then making a very accurate, but very wrong set of plans 🙂 This is why my woodwork teacher used to chant “measure twice, cut once” at us.

I’ll put the plans and a writeup online once I’ve begun cutting and sticking wood. Tomorrow will be spent driving around in a van and then moving my room about. I also need to arrange for the council to remove my old sofa since both won’t fit in my house together (or so I am lead to believe… maybe they will… hmm…). Can’t get on the council’s website though, it’s having problems.

Connects2 CTACTIPOD003 Citroen C3 iPod Adapter

The other day I ordered a Connects2 iPod adapter for my Citroen C3 car. The adapter connects my iPod Touch to my car stereo’s CD changer port, allowing the car to control my iPod. I can now switch tracks, adjust volume and choose playlists using the controls on the front of my car stereo, or the ones on the steering wheel.

Fitting it was quite easy, the Connects2 device being a small silver box and some wire. The hardest part, as ususal, was getting the car stereo out. I have taken photos of the process, and will write it up later on. For now here are a few photos.

FM Transmitter, iPod charging cable and double plug
FM Transmitter, iPod charging cable and double plug
Connects2 CTACTIPOD003 Citroen C3 iPod Adapter
Connects2 CTACTIPOD003 Citroen C3 iPod Adapter
Testing the setup works
Testing the setup works
Finished installation of the Connects2 iPod adapter with iPod Touch
Finished installation of the Connects2 iPod adapter with iPod Touch

Tagging my photo galleries

I run two photo galleries; a hand-picked collection of my best photos over at Landscape Photography, and a general gallery of all my photos. I’ve just installed the Gallery2 tags module on them to make finding photos easier, so rather than having to search by only the names of the files or words in the description there are now clickable tags that can be added, the idea being to link related photos together.

Tagging photos is easy if the content of the photo is used for tags, rather than its location or other non-visual information. For example, the following image

Burnt out car
Burnt out car

was taken in Wiltshire, and is of a burnt out car. The tags for the photo, however are

since that’s what I can see in the photo. I can’t see ‘Wiltshire’ or even ‘car fire’ (because it’s not on fire – tags must be accurate for this to work), but I can see some trees, some blue sky, a bit of frost and the melted bit at the front of the car where the bumper used to be. Tagging photos this way is simple if I imagine trying to describe the photo to someone. Tags should also be generic and re-usable, their puprose is to link items together. Having thousands of tags, each with only one photo is no good, if I do that I may as well just write a really good description instead.