Monthly Archives: May 2008

Nixie Kitchen Timer


I have long been dissatisfied with the inflexibility of the humble kitchen timer. The old clockwork ones had an excuse – with a purely mechanical device, one can't just "fix it up in software". Electronic kitchen timers that I have come across tend to have up/down buttons for setting the time and a start/stop button to set the thing running or get it to stop again (and possibly cancel the alarm before he noise drives one mad.)

Whilst most of my cooking doesn't call for timing of any precision, or even of fixed intervals ('cook until it turns brown' rather than 'cook for n minutes'), there are tasks where I do need timing, the main one being batch frying. When preparing my beef'n'buckwheat schnitzels (tenderised slices of topside of beef deep-fried in a spiced buckwheat batter), I cook these one-by-one for 3 minutes a piece, then putting them into the warming cupboard (actually the oven set to about 70 degrees Celsius).

Trying to read 3 minutes of the oven clock is not easy – if I note the time and then wait for that time to read the original time plus 3 minutes, I could be out by nearly a minute either way due to the lack of a seconds display. Not only that, but I have to remember to note the time as soon as I put the piece into the fat and then watch the clock without getting distracted. If I were to use a kitchen timer, I would either have to deal with the imprecision of a mechanical one (not good for short periods) or fiddle around for nearly the full 3 minutes trying to set an electronic one – for every piece that I cook.

Original Solution

Thinking over this issue, I created a set of specifications for my own timer:

  • Work in minutes only (I know the lower end of my 60-times-table well enough) – timer to run from 000-999 minutes
  • Time set by a set of 3 BCD switches; the type under consideration has up/down buttons per digit.
  • Time displayed on an array of 3, multiplexed, 7-segment LEDs
  • Use decimal points of display to indicate position in minute (1 lit=15s, 2 lit=30s, 3 lit=45s); finer resolution not required for my type of cooking.
  • Provide up/down count with audible alarm when down count reaches zero; count direction determined by a toggle switch
  • Audible alarm to run only for a few seconds – digits should flash on alarm condition until stopped
  • Pause/stop push-button pauses count on first press, on second press stops and resets count to values set by BCD switches. Clears alarm condition when pressed after end of countdown.
  • Start button sets timer running, resets count and starts again if pressed when unit running. If unit is in end of count alarm condition, clears alarm, resets and starts running again.
  • On/Off toggle switch isolates unit power
  • Unit controlled by 8-bit microcontroller taking timing signal from 32768Hz crystal. (Probably use Atmel AT90S8535, since I've got one kicking around doing nothing)
  • Unit runs from a 12V wall-wart; logic voltage is provided by an LM2576-5 'Simple Switcher' from National Semiconductor (I got a job lot off eBay recently).

This design would mean that I would only need to set the BCD switches to 003 and press start at the beginning of the process. Each time I put a new piece in the fryer, I would just have to press start again. Simple!

Short-Lived Tubes

A couple of days ago, I spotted some Nixie tubes on eBay – 18 x ??-12 (IN-12 for those whose displays do not support the Cyrillic alphabet) tubes with sockets for an "I can't believe it's so cheap" price. I immediately bought them (before anyone else did) and only then had a look at the specification sheet. These units are only given a rated life of 7500 hours. For intermittent use, this is OK; however, I was going to be putting these into clocks – having the tubes burn out in less than a year makes them less than suitable for such an application. They still look to be nice tubes; socket mount simplifies PCB design considerably as I can just run a 0.01" ribbon cable from the board and split it up at the socket. I also like the profile of these top-reading tubes. What to do with them?

My kitchen timer once again drifted into my mind. Rather than messing around trying to drive 3 lots of 7 LED segments and all the lookup tables that involves (without using dedicated chips), I can just use a BCD to decimal decoder, 10 HV NPN transistors to connect them to the Nixie cathodes and 3 HV PNP to sit in the anode circuits to handle the muliplexing. Other than requiring a second power supply to provide the 170V B+ for the tubes, the design is no more complicated than the one using LEDs and out of LEDs and Nixie tubes, I know which I would rather have to look at.

The Story So Far

The tubes are somewhere between here and the Ukraine; I believe that I have all other parts to hand, although I may acquire a new 32768Hz crystal rather than using a cannibalised one. Software does not look to be too much of a challenge – switch debouncing is new to me so I may even cheat and see if I can find a keyboard scanner chip or somesuch that will do the job for me and can be interrogated via an I2C or SPI bus.

Stay tuned!


  • Nixie discussion group and resources on the NEONIXIE-L Yahoo Group.
  • My original set of Nixie tubes and the ones that are on their way come from eBay member mycomponent in the Ukraine.  This vendor doesn't always have Nixie tubes listed, but often has Russian vacuum tubes (valves).

Stir-Fried Duckling Breast with Orange and Carob


There was a time when Christmas Dinner was supposed to be a special meal. Granted, it is not every day that one would cook an over-sized turkey, the 'left-overs' of which will still be being consumed right through to Candlemas, if they are not fed to the dog before this time. To the gourmet (or gourmand) that is Smiffy, every meal should be special and turkey is only suited as a bulk base for a poultry curry. This is why, last Christmas, I decided to prepare something that was not only special, but was also different from my normal fare.

A Duck!

Duck is not the easiest thing to find round here. Luckily, our butcher is able to get in frozen catering packs of duckling breasts (10 breasts, 1.5kg nett). Packs of 3 or 4 breasts would probably be more convenient – a pack this size means 3 duck meals in a week unless one has guests or a large family.

If you have a source of fresh duckling breasts or are able to buy them in any quantity, I would allow two per person.

Take Stock

To get things in the correct chronological order, we need to start out by making our fake duck stock. First, catch your duck. Er, I meat defrost the duckling breasts, if frozen. Skin as many of the breasts as you are going to use, or even all of them if you feel like it. Put the skins in a pressure cooker or stock pot with a chicken carcass (either get a raw carcass from the butcher or use the remains of a roast chicken). Pressure cook for 2 hours or simmer for 4-5 hours in the stock pot. Strain out all the bits, cool, refrigerate for at least six hours, then strain off the fat.

Making a Meal of It

Prepare a risotto of Arborio rice, Shitake mushrooms, onion, a splash of basamic vinegar, a little garlic (not too much), salt, pepper and fake duck stock. Any "luxury" mushrooms like dried Chanterelles can also be added to this provided that they do not have too strong a flavour. Cèpes (Porcini mushrooms) would overwhelm this dish.

When the risotto is under way, cut up the duckling breasts and pop them into a wok (not too hot) with a neutral-flavoured oil. When the pieces have cooked for a little while and changed colour all over, add orange juice (preferably fresh), a little white wine and a couple of tablespoons of carob syrup (in Australia, available from Macarob). The amount of liquid is not very critical as we now reduce this until it begins to caramelise.

When ready, add a little (but not too much) truffle oil to the risotto and stir in well.

Serve with a good brut Champagne, or something similar like Thorogoods Misty Morning.

Variations on a Theme

  • Rather than using a neutral oil for, try sesame oil.
  • Serve with noodles rather than risotto.

Book Review: The Short Bus

Blogging Against Disablism Day


I was contacted by Jonathan Mooney a little while ago and asked if I would be interested in writing a review of his book ‘The Short Bus’, subtitled ‘A Journey Beyond Normal’. It seemed to me that it would be very fitting if I were to write this review and publish it as part of the proceedings of Blogging Against Disablism Day 2008.

Jonathan is one of those people who was badly let down by the education system – badly dyslexic, a ne’er-do-well who would quite obviously never get anywhere in life. So thought the education system. Although Jonathan almost lost hope himself, he proved the doubters wrong (don’t you just love it when that happens?), graduating from Brown University – with honours. Jonathan is now an author, speaker, and consultant, helping students, parents and educators; for details of what he gets up to nowadays (and how he may be able to help you), have a look at Jonathan’s web site.

The Short Bus

What is a short bus? Before I first picked up the book, I had no idea what a short bus was, so an explanation for those who share my ingnorance is probably in order. A short bus is just that – a shorter version of the American school bus that we see on the movies (and Americans doubtless see on the streets), generally used to transport students with various disabilities to educational facilities where their needs might best be met. I say this with a certain amount of sarcasm as Jonathan’s book suggests to me that both the assessment and meeting of needs falls short of what might be desirable.

Jonathan’s plan, as an adult, was to acquire a short bus, the symbol of his experiences with Special Education, convert it into an RV (Recreational Vehicle) and tour the USA for a couple of months, meeting people like himself who were considered ‘not normal’ by the educational establishment and had been let down by that same establishment but had then gone on to succeed in their own way – for their own given value of ‘normal’.

An Eye-Opener

With my mother having worked as a dyslexia consultant for some time, I was well aware of how students could be let down by the system. Reading Jonathan’s accounts is a real eye-opener, if not shocking in what it reveals. The inhumanity of the system and the educational ‘experts’ is brought into sharp relief by the humanity of Jonathan’s writing.

The book is also an eye-opener in a more positive way and allows me to trot out my much-use phrase, “for a given value of normal” when we see how supposedly not-normal people can succeed and prosper, despite the best efforts of the education system to break their spirits.

I could waffle on for ages and give you a potted summary of the book, but what would be the point? To really do this book justice I have just to present this advice: go out and buy/read it. Jonathan’s style is very engaging, very humane and – above all – very readable. Not bad for someone who was supposed not to be able to read and write.

The Short Bus by Jonathan Mooney is published by Henry Holt and is available from Amazon, Barnes & Noble and other good booksellers.

This book contains occasional coarse language.