Numitron Tube Clock

Vacuum tubes make me drool: I think that every good piece of electronics should be bathed in an orange glow and if I had my way none of us would be messing around with these transistor doodads, they’re bad news I tell you, you can’t see ’em working!
However, this project would be pretty tough without them, so I’ll begrudgingly accept their help for a while…

Any of you that are familiar with DIY electronics will have no doubt come across Nixie tube clocks at some point and considered a remake. After a bit of researching though, it seems that while there are kit options out there, they do involve high voltages which brings a whole new hassle with it.

There is an option which avoids this and uses much cheaper tubes to boot: The IV-9, also know as the Numitron. Not only do they have a brilliant name, but they also only require 3-5V to illuminate. I went on eBay and ordered half a dozen from Russia and within a couple of weeks they’d arrived at my door, with not a datasheet in sight, damn.
A few Google searches later and I managed to find one in Russian, but the pinouts are there so it’s not a big issue:
IV-9 Datasheet

The overall plan is this:
Working from Jon Stanley’s design I will build a single digit Numitron clock. Simple.
But I will write the code myself to keep myself up to speed with Assembler for my university course next year. Theoretically simple, but in reality, probably not so.

I’ve currently got one of the tubes hooked up to confirm the pinout and check that none of the filaments have blown; new old stock is always a bit of a gamble but these all appear to be fine. Apologies for how washed out the image is, my camera didn’t cope too well for some reason.

Single Numitron tube

 The tube will display one digit at a time, with four yellow/orange LEDs to show which hour and minute value is on display. I’m hoping to run the shebang from a PIC16F84A as Jon has, this depends on how bloated my code gets, but I should be fine.
I think I’ll get this up and running on a breadboard first, then transfer it straight over to a PCB, DorkbotPDX do a great job and at a crazily low price. When this happens I’ll pop the files up here, it’ll probably be in a couple of weeks though, I should be revising now. Back to the books!

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A little taste test

So today I rediscovered the joys of the sampling programs that electronics companies offer. There’s a fairly handy list here which I’ve slowly been working through for an hour or so.

Before I get any angry comments, I appreciate that the nature of these sample programs is to provide options for engineers already involved in the industry, but another side of this is also to get the brand recognised by a younger generation of students coming through; I’m using this clause to justify it…

Starting with Microchip seemed to make the most sense. My university’s curriculum seems to focus fairly heavily on PIC microcontrollers, specifically the PIC16F84 because of how hugely widespread it is. The programmers are also fairly cheap, a quick search on eBay for “PIC USB K150” will bring up the model I bought last night; I can’t complain for £10 with a ZIF connecter.
I managed to tap Microchip for a couple of PIC16LF84A chips, one in in a through-hole package and one in a SOIC, just in case.

Texas Instruments are known to have one of the most generous sample programs so they were second:
They recently launched the TI Launchpad to show off their low-power uCs and while you can get this for a grand total of £3.26 at Mouser, they will happily slap a £12 shipping charge on top of this which makes it far less desirable for me. I’ll definitely bundle it in on my next Mouser order though, simply because I’ll need a programmer for the two MSP430G2211 uCs that are in the post to me at the moment…
Also winging it’s way from TI HQ is a TMP100 I2C temperature sensor, a BQ32000 serial real-time clock, and a RC4560 dual channel audio op-amp. I’ve picked up the sensor and RTC because I want to experiment with different communications protocols, it seems to be that I2C is the way forwards with sensors and I feel left behind!
The op-amp is for a possible simplification to the EMG circuit that I’m working on, but that can wait until the original boards are working first!

I’ve sampled from Maxim before and found them to be very good. This time I was searching for a simple IR sensor pair and came across this little beauty. It appears to be very similar to the sensor in most touchscreen phones which detects the proximity of the face to the phone as well as ambient light. I reckon I can probably twist this into service in some form of project, so I’ve ordered two. They’ll be an exercise in soldering anyway… They’re TINY!

No sample raid would be complete without an enclosure, so I contacted Serpac and asked for one of their H67 enclosures. While the rest of the samples will be used in future projects, this one will be used to case up my digital ‘scope, it sounds like it’ll fit like a glove.

The last place I contacted was Bulgin, who make some really high quality switches intended for outdoor applications. I’ve asked for a couple of their MPL027 buttons, so we’ll see what comes of that!

Note: I would’ve asked for a couple of enclosures from Pactec, but they were going to charge shipping costs and little old me is a tight wad.

Update: 6/2/12 – The Texas Instruments order came today, everything as expected and a nice note on the bottom saying “Do not try and make a payment for this order”. Okay then!

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A quick introduction

Hi all,

I’ve been intending to start a blog for ages now and I’ve only just got round to it. This will serve to document my fairly varied interests and forays into making; I tend to take a scattergun approach to hobbies so hopefully this will give me the motivation to keep on track with just the one at a time!

I’m a first year Electronic Engineering student in the UK at the moment and as such have a pretty keen interest in electronics. This accounts for a fair amount of the projects I have on the go, but I’ve also dabbled in leatherworking, lost wax casting and various other crafts.

Projects on the go:

I’ll try and cover all of these over the next few posts, although I’m quite tempted to attempt a small sumo robot as well, so we’ll see how it goes. Until next time,

Dave

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