Archive for the ‘Radio and Electronics’ Category

HomeAutomationHub now in use

Sunday, September 18th, 2011

This week saw the introduction of the Home Automation Hub which I put together last weekend. The primary function so far is to act as a bridge for the Current Cost monitor system and Pachube. This has replaced my old solution which collected data into a local MySQL database and then sent averaged results to Pachube. This was somewhat inefficient and not easy to extend. the HAH means that I have now been able to integrate the Individual Applicance Modules that work with the CC unit – so Pachube presently has five streams of data.

One of these streams will allow me, for the first time, to reliably monitor the power consumption of the Christmas Lights. I previously tried to do this with a Maplin plug-in monitor which melted a few years ago making an odd smell and posed something of an unexpected danger!

Construction was fairly straightforward, however this is not a project to the novice constructor and a reasonable level of skill in working without highly detailed instructions was necessary. Nothing particularly difficult, though, and it worked first time. It took longer to get to grips with configuration of the data streams as this requires some careful reading and interpretation of the notes. I have yet to work out the best way to try and integrate things with the X10 house control system – and if it won’t work directly the xAP system which is deeply embedded looks promising.

The HAH will allow for additional functions in due course, perhaps one day to include a garden watering system – pending getting A Round Tuit.
Graph of electricity consumption via Pachube

NixieTherm Kit

Sunday, July 10th, 2011

This is a novel electronic thermometer with a linear display looking just like a real glass thermometer, but based on nixie tube technology dating back to the sixties and seventies. It came from here:

I spent an afternoon building this kit whilst S&G were out on Saturday. Overall I think it was a great success and a fine kit with good instructions. Started by laying out the various packages from the box and inspecting the bits and pieces.

These are the packs of bits for the nixietherm kit

NixieTherm components

Accompanied by a pretty good set of instructions I then proceeded to mount all the PCB components, sticking to the recommended order which made pretty reasonable sense (resistors, capacitors…. and so on). All the components fitted just fine – no “fine tuning” required. The PCB is through plated, and although some of the pads were small, with a suitable iron posed no issues. I used a very fine lead solder which worked well. [Not yet experienced lead free solder so I don’t know how much more difficult it might be, although having read around the subject a bit I don’t expect it’s as bad as I imagine.] Once all the parts were mounted there were a number of test voltage measurements to make and a crude calibration was completed. Completed PCB for the nixietherm
The next stage was to burn-in the display tube. These Russian made components have been sitting in a warehouse for probably over twenty years. The result is that the linear display doesn’t light up all the way along the tube at first use. This is fixed by running the tube for an hour or so at a slightly higher than normal current. There are some pads to jumper on the PCB to set this up, and after then removing the op-amp the burn-in commenced. After about an hour and a quarter I couldn’t detect any improvement in the display’s range so that task was done.

Burn-in phase of nixietherm construction

Burn-in phase of Nixietherm construction

So after the burn-in was completed the next steps are to remove the burn-in jumpers and commence mechanical construction. The thermometer is housed in a neat case made of laser-cut perspex sections, and the display tube itself is supported in a cut-out section of perspex so as to resemble a conventional glass/mercury thermometer.

The first stage was to mount the vertical section for the display tube, upside-down, in a vice (or in my case, a large G-clamp to simulate a vice). Slide the tube into the cut-out with a couple of perspex supports, and then you continue to build the case from the top down. Some care required to make sure the bits will end the right way up and facing forward. All the mechanicals were in the kit – nuts, bolts, washers, spacers etc – and this was a fairly straightforward set of steps to work on. The final result when removed from the supporting “vice” was very pleasant.

The Nixietherm was left running overnight before re-calibration in the morning and a subsequent trimming later in the day so as to end up with a good looking and effective desk thermometer.

Finished Nixietherm

Finished Nixietherm

Regen Radio Kit

Saturday, June 19th, 2010

I have just completed a kit for a valve radio – a regenerative detector type. I bought the kit a few months ago from and with Serena and Grace both at the hairdresser’s this morning I had a few hours P&Q to fill so out came the kit, soldering iron and tools.

It’s quite novel in that it only uses a 12v power source – possible to run from dry cells if you’re feeling extravagant – but that’s the highest voltage in the circuit – so it’s very safe; no need for caution when touching contacts tracing faults with my soldering. Yep – there was a dry joint somewhere – I suspect on the variable tuning cap, but once sorted much sound came from the speaker, notably the sound of the vuvuzela horn.

Some confusion when troubleshooting – the engraved legend on the front panel has somehow got the “Vol” and “Regen” transposed!

Edit: After mentioning the issue to the kit’s creator he’s pointed out that I didn’t follow the instructions and that I should have connected the pots with wires instead of directly to the PCB. It’s still a great little kit, though.

Visiting New Scientist

Wednesday, March 17th, 2010

Today I spent the day visiting my New Scientist colleagues at their offices in Theobald’s Road in Holborn, London. Holborn’s a bit of an old stomping ground as I used to work there for a while for the bank (in the Old Prudential Building) so it was with mixed feelings that I made my way to the area today.

In the sunshine, like today, it’s a fine looking area, and not nearly as depressing as I thought it might be. In any event, meeting the people was great fun, and we went out for a pub lunch in Lamb’s Conduit Street.

There was time during the day for a good chat with all the devs; Ken, Matteo, Vivienne, Neela, Ruth and Rowan. Most worthwhile, and I think I’ll do this again in a couple of months.

New jammer worked great on the train in the way home. Very amusing as well.

Arduino Arrives

Wednesday, February 10th, 2010

Today saw the long awaited arrival of an Arduino starter kit. Ordered from oomlout a couple of days ago it’s arrived in good time, and made a great impression.
The kit itself is neat, tidy and very well presented in a plastic compartment box – so no cause for untidiness or losing anything – together with a great little guide to getting started. The guide, as well as some handy introductory material about the kit, programming and electronic components. After that each page takes you through constructing a small experiment – working up in complexity and using all the components in the kit.
I chose to install the IDE on my eee 1000H netbook rather than my desktop as it had a much more up to date Ubuntu installation which met the requirements without any further hassle.

A first Arduino Experiment - flashing LED

Arduino flashing a LED

I started with the first example – to make a LED blink – and discovered how case sensitive the sketch seems to be – but it was easy to work out where I was wrong from the way it debugged during the compile and highlighted the offending line.
A very quick upload later and the LED was blinking merrily away. So easy to change the mark/space ratio by altering the delays in the loop and uploading again. How easy is that?
I see much time to be spent playing and learning how to get the best from this. Very satsifying indeed.

Possible Arduino Projects

Tuesday, February 2nd, 2010

This is really just a short note to file away for the future.  Having recently discovered the Arduino, and seem many of the things it’s been made to do, I wanted to jot down a few ideas I might follow up myself one day.  Real Work seems to get in the  way most of the time, but with a long history of dabbling in radio and electronics and having built many gadgets, radios, remote controls and so forth, the Arduino looks like a fab  way to interface with mechanicals.

So the first idea is a way to play some little bells to make tunes.  I have a couple of sets of mini bells from B&Q some years ago which play a fixed set of Christmas tunes, controlled from a small box and a 12v supply.  If I can interface each bell line to the Arduino using a (reed) relay [or even directly, perhaps?] I’d have an eight note one octave player.  A quick look on the ‘net shows someone has made a similar bell tower from hand bells, however I’d like to be able to play more than one note at a time.  Input from a text file of some sort – I’ve seen a form of music notation that might do the trick, but this needs more investigation.  Ultimately I could build a multi-octave machine like a player piano or adapt a harmonium.

Second Idea: Temperature sensors on the heating system to measure use and efficiency – and combine with a gas meter reader to complete the energy consumption records  via Pachube (i.e. to add the the electric consumption data).

Third idea: Talking parrot, an adaptation of an ambient orb.  I have a USB parrot which only works on Win and has no recent drivers or apparent way to use in Linux/OSX – so I’m going to keep it for possible hacking in the future.  Flap wings or nod head , open beak etc to relay data values of some sort.  The higher the home energy use, the more the little bird will fidget.

Today’s Roundup

Tuesday, January 19th, 2010

Well, a number of things to think about today; first the lead developer on one of our magazines told me he was leaving the organisation.  I’ve really enjoyed working with him over the past two or three years, but I wish hime every success in whatever he moves on to.  He’s young enough and without ties such that it could be anything, anywhere.  Good luck, Ken.

Secondly, Amazon have finally given a date for the Practical Arduino book to arrive (well, not “a” date, but a range of dates) but at last it’s on its way.  Have been reading more on-line snippets and trying to formulate a few ideas about what to choose as a project; many ideas floating around, so once I get used to the gadget I’ll have plenty to choose from.  The elctronics bit isn’t a problem, but I do wonder how well I’ll get on with the programming side of things.  I’ll just have to do what I do with everything else and adapt what I can find that’s almost what I want.

Work threw up few challenges, but I had to get the IRC client working again.  No reply to my question on the #movabletype channel, but I answered myself anyway within a few minutes, and I guess most of the Americans were probably still in bed anyway.   I finished my scheme for excluding IP addresses from the blog infrastructure – mainly to stop search and other bots wasting cgi-bin resources, but I did have problems during the day with a Chineese e-mail address scraper which caused some outages of part of the system.  Hopefully, not any more!