I was taking some photos of phones and stuff this afternoon, and Penny decided she wanted to join in.  As ever, her joining in involved wandering into shot, lying down and licking her bits.

In phone exchange news – it’s all working! I can make calls through my ATE 10 line PAX.  Hurrah!  Video will follow just as s0on as I manage to find my youtube password.

This is going to be my entry to this weeks photo-challenge on the theme of music.  I had weekend plans to find a bandstand (failed) and I had lighting plans to bounce a reflected piece of music off the pick card/finger plate of one of my guitars (failed due to a dud flash trigger)

So, one light, 30p worth of sheet music from a charity shop and a pair of glasses I found in the back of my car – and I give you the above.  Not my best work but certainly not my worst.

Left to right we have “Let me take you there” – Stonedrive and “I believe” – Happy Clappers.

You can tell from the pixels.

I did take a few photos (inbetween designing and playing with phone exchanges) but they weren’t really up to much.  This is the best of the bunch, and it’s an interior view of a road menders living wagon.

This is why I haven’t been taking photos or updating my blog this month.

What you are looking at, is the beginning of the telephone exchange I’m designing and building from old GPO components and circuit techniques. I’m designing it from scratch, picking and choosing circuit elements from various telephone exchange designs from the 1930s-50s.

Tonight, I managed to build the first two line circuits (there are enough relays in the image above for four line circuits, but better to start small!)  After a little bit of debugging (the connection tabs on the back of those relays are really confusing!) all the bits of wire have the voltages I’m expecting on them!  Yay!

Some of my prototyping methods are a bit vintage as well.  These are copper coated nails, which are used to make an impromptu wirewrap board.  This particular bit of prototyping is the subs-multiple.

The stuff I’ve built doesn’t really do much at the moment (apart from click a bit when you pick up a phone) and the next stage is to build the linefinder.  That bit is much more interesting as it spins round and makes nice raspberry noises.

I wonder if my video camera still works

I’ve done some reading around on this, and happened to find an appropriate section of “Telephony – Volume 1″  by J. Atkinson (Volume 1, Pages 432-433) which describes the alarm fuses I’ve got on my AT&E PAX.

It doesn’t quite marry up with the information I got through the THG mailing list, so I’m not sure what to trust more – I’m inclined to go with the book as it’s probably more reliable than memory – although I may check with the list to see if it’s a known error in the book, or if it was a case of falible memory.

Perhaps I should check my physics textbooks next, perhaps I’ll turn up a formula for calculating the fusible current for a given diameter strand of copper wire…

The AT&E 10/2 PAX (10 line electromechanical phone exchange) I’m restoring has some interesting fuses in it.

They’re designed so that when the piece of fuse wire blows, the flag pops up to let you know which fuse has blown, and a strip of metal pops down to make contact with a bar running the length of the fuse board.  This bar is connected to an alarm circuit. If a fuse blows, the alarm circuit activates and a light comes on to tell you about it.

The idea is similar to the fuses I’m used to seeing on the UAX/PABX kit we’ve got at the railway, although they’ve just got two sprung contacts instead of cool little flags.

I’ve done a reasonable amount of googling for every search term I can think of, but can’t find any information about this particular type of fuse (let alone a source for replacements!)

I assume that the colour of the flag (red, blue or black) denotes the value of the fuse, and whilst there are part numbers stamped on the ends, there are no values.  The markings are as follows:

I assume the marks in the Horizontal Slot column are model numbers, but I’m not sure what the “31/n” bit is about, especially as it doesn’t match up with the last three digits of the model number.

So – has anyone got any ideas where I could get some more of these fuses? Has anyone got any ideas what value fuse wire I should attempt to repair (or replace) them with?

Last weeks photo-challenge was “product shots” so I sketched out some ideas and headed to the shops. 2 bags of ice, a large roll of foil and a can of sprite later – I shot this in my front room.

It’s not the most original photo of a soft drinks can, but I was aiming for “compitently executed” rather than “exciting and edgy” – as I was looking through the outtake shots, I saw a couple of happy accidents which have sparked a few ideas about what Icould have done differently – so I’m going to revisit the idea at some point.

Ian came round after work today, to help me unload this from my car (where it’s been since Sunday morning when I bought it) as I can’t lift it on my own!

It’s an ATE 10-2 PAX, which is a 10 line electromechanical phone exchange (lots of buzzing, clicking and whirring bits in there!) – designed for small business/factory use, it was built by the Automatic Telephone & Electric Co Ltd, of Liverpool.

It’s missing its power unit, and only one of the line fuses is intact, but otherwise it appears to be complete.

My plan is as follows:

• Get hold of some diagrams for it
• Build a new PSU for it (probably based around some lead acid batteries and a charger)
• Get it working
• Strip the case down, and have it shot blasted and repainted
• Possibly build a new front door for it out of perspex, so you can watch it do its thing as you dial
• Build a plinth for it with casters so I can move it about more easily
• I’m also hoping to build an appropriate relay set to get it talking to CNET

First things first though, it’s been sat in a garrage for years and is filthy, so my first job is to give it a clean!

At the railway on Saturday, we spent all morning digging a trench so that we can bury some conduit accross a gate. Being a deskbound sysadmin, it made a nice change to be outside doing some real work!  Left to right we’ve got Ian, David (the level crossing operator), and John.

From this angle, it doesn’t look like much of a trench. So here’s a long shot.

And in one post, I’ve managed to equal Mays photo count.  It’s all downhill from here!