Akafugu VFD Modular Clock by Manuel Azevedo

Intro

I discovered this wonderful tiny VFD clock by chance, while browsing Tindie for novelties. As I’m a newcomer to this Nixie/VFD world, I was not aware that Brian Stuckey already did an article in 2014 on a previous incarnation of this clock (Akafugu Modular VFD Clock).

I contacted Per Johan Groland, owner of the Japanese maker Akafugu that makes these clocks, for all the shields I could get my hands on - The only shield I did not order was the 4 tube IN-4/17 shield, which Brian already tested and which I find does not do this clock justice.

The VFD Modular clock arrived as a kit. Shipping from Japan to Switzerland took less than two weeks. All the parts are well packed, each in its own bag. The PCBs have a glossy black solder mask with golden ENIG finish.

A USB cable is also included. The main PCB is protected in its own bag. You can order the tubes from Akafugu. If you have already ordered tubes from elsewhere, like eBay, it’s also possible to order the clock without tubes. This clock can be ordered in Akafugu’s own shop, Tindie or eBay. For custom orders, like ordering several or only specific shields, it’s preferable to contact Akafugu via email. It’s also possible to order acrylic cases.

Per also shipped the 6 tube IV-4/17, the IV-18, the IV-22 and the IV-6 shields. I did not order a case, as I intend in the future to make my own. At the risk of repeating some of what Brian already said, I'll perform a full review of all the shields except the one that was already reviewed. It's important that this review be self contained and that you don't have to make reference to previous articles.

The clock has two parts - the clock base board and the tube shields.

Base board

The base board size is just 100x35mm big. It uses 10mm nylon spacers so the PCB does not sit directly on the surface.

On both left and right sides of the board there are two pin headers - this is where the shields will connect to.

There are two buttons, confusingly labelled S1 and S2, where S1 is “Button 2” and S2 is “Button 1” on the back side of the PCB. There’s also a two-position switch that enables or disables the alarm. This is an interesting point - where one can control the alarm with a switch instead of entering menus to enable/disable it. This is a lot quicker and easier than fiddling around in menus, especially if you are sleepy.

On shields that support dots, the alarm enabled indicator is shown as the rightmost dot or a big dot (IV-18 shield).

Also on the backside there’s a USB mini connector - you can use this connector to power the clock, as well to program it. On the front of the board there are two LEDs - one blinks when your power-on the board - and the other blinks when the board is being programmed.

There’s additionally a SMT switch that resets the clock.

Underneath the clock there’s a row of pins compatible with Adafruit’s GPS module. Any GPS or GPS emulator, like nwts, should work with this clock, if connecting at TTL levels and if supporting 4800 or 9600 bps. The clock uses the $GPRMC NMEA string to get its time. It will synchronize the time every 1 minute. The clock supplies 5V to power the GPS module.

 The main components of the base board are:

• ATmega32U4RC: 32K bytes 8 bit MCU with ISP flash and USB controller
• DS3231: Extremely Accurate I²C-Integrated RTC/TCXO/Crystal
• MAX 1771: Step up DC-DC controller
• 24LC512: 512Kb (64KB) EEPROM
• HV5812: 20 channel VFD display driver

There’s also a description of an I²C temperature/humidity sensor on the clock’s schematics, but this is not included in the board. Currently the clock derives its temperature from the RTC chip – but as the clock warms up a bit, this temperature is always a few degrees higher. Measuring with a laser temperature sensor, the temperature reported matches the RTC surface temperature.

The ATmega is preloaded with an Arduino Leonardo bootloader – this allows programing the open source firmware using just a USB cable and the Arduino IDE. Also included are ICSP pads on the underside of the board, but these require a pogo-pin adapter to be able to use them.

This probably the clock’s greatest strength: it’s completely open source. The current firmware code is published on GitHub.

Finally, there’s a 3.3V CR1220 battery holder to allow the RTC to maintain the current time in case the clock gets disconnected from power.

The shields

The following shields are available:

• 4 tube IV-4/IV-17 shield

 

• 6 tube IV-4/IV-17 shield

• 6 tube IV-6 shield

• 1 tube 8 digit IV-18 shield

• 6 tube IV-22 shield

A really nice touch is that the clock detects what shield is connected by a 3-bit pattern and adapts itself to show the correct display for the different tubes, there is no need to set any thing up for the different shields.

Every shield has a hole for each tube, with grooves for each tube’s wire contacts. Before soldering the tube, extending the wires outward and placing them in the grooves, allows for an easy alignment and soldering. It also makes it possible to replace a tube easily.

The IV-22 shield uses expensive Harwin tube sockets, the same as used in other clock models from other manufacturers - this allows an even easier replacement of the tubes.

The IV-6 and IV-22 tube shields are very similar on their display capabilities - the only difference being the size and orientation. The clock operates very similar with these tubes.

The IV-18 shield has two additional digits, making use the two additional digits for longer scroll and FLW animations. Also uses the big dot on those tubes as an alarm indicator.

The IV-4/IV-17 shields use the tube’s sixteen-segment display to display real letters; on the seven segment tubes, we can only guess what letter is shown, on the sixteen-segment tubes this works out very well. However, due to the additional segments, disappointingly, this module does not have any dots.

All the shields except the IV-18 have additional I2C pins that allow future expansion!

Usage

Starting the clock for the first time, the Load LED will pulse for about 8 seconds, after that the display will show which shield is loaded.

The clock will then display the time/date/temperature/four letter words/message on the display, depending on the configured parameters.

The menu system is simple and efficient, but takes some time to get used to.

Button 1 advances to the next menu item. Button 2 changes that item value. If a menu item ends with a dash, this means there’s a sub-menu. Pressing Button 2 enters that sub-menu and again Button 1 moves to the next item and Button 2 changes that menu value. It can take some time to get used to it, or to try to decipher the characters on the seven-segment displays.

The full menu I could derive from the source code is:

Toggling the alarm switch enables or disables the alarm. On all shields except the IV-4/IV-17shields there’s a dot that indicates the alarm is on.

The clock supports 12/24 hours, day/month/year, month/day/year and year/month/day formats.

The display can also be dimmed – automatic dim times can also be defined.

Also, another good option is to set DST rules – though it might get a little bit tricky to master.

The alarm volume can also be changed.

GPS settings are the normal ones we can find on other clocks, like setting the baud-rate, GMT hour and minute difference and some GPS debug options to troubleshoot GPS problems.

Firmware customization

Exploring the code, some interesting things can be found:

• Define messages for specific dates: Special messages that will be triggered on a certain date can be coded into the software
• Control LEDs via I2C
• Use a rotary encoder
• Use additional temperature, atmospheric pressure or humidity sensors

To compile the code, it requires the necessary WireRTC control library, that’s also available in the standard Arduino distribution. The code shows many available options and it’s quite big, but it seems easy to read and understand.

Some of the extra options, like the pressure and humidity are undocumented, only existing on the source code – no wiring or parts are described on the documentation. Presumably these are for future expansion.

What was not so good

Before my final thoughts, I’d like to point out that there are some areas that require some improvement.

The documentation on the site, though mostly complete, requires some clean-up and the removal of some ambiguities, like references to parts that don’t exist anymore. It’s clear that improvements are being added both to the hardware and the software and those are not reflected in documentation, making it sometimes a little bit frustrating. Akafugu acknowledged those problems and is currently fixing them up. Some of the clean-up is already in place when this review was published.

One of the main “faults” I’d like to point out is a missing complete table that includes all the menus of the device and a matrix with each shield features. I’m sure this would help many buyers deciding.

Another page that requires some cleaning is the Resources page. A clear place where to find schematics, manuals and links to the software would be something that would make the experience less frustrating. Though the clock schematic is available, I couldn’t find the shields schematics - they might be important when troubleshooting tube problems, because the way each shield is driven is considerably different from the others.

On the clock software, I’ve noticed that some features work sporadically, like the Four-Letter Word display – sometimes the tubes are just blank. I’m not sure if this is an issue of a specific shield, but usually a restart of the clock solves this issue. Akafugu suggested to check if the EEPROM chip connections or adding a decoupling cap, but since I started this review, the problem did not happen again.

Final thoughts

The device is very well made – it clear that it has already some years of development and fine-tuning. The fact that the source code is available, makes this device very desirable for hacking, customization and general learning on how to make a Nixie or a VFD clock.

Assembling the kit is relatively easy once some of the ambiguities of the documentation are solved. The hole with groves method of assembling wire tubes is very useful!

It’s a pretty device and an excellent use of several VFD tubes.

Communication with Akafugu has always been excellent – Per Johan Groland has been very communicative and ready to help with any questions asked.

I’d recommend this device for all those that like VFDs, a small beautiful clock or a piece of hardware you can also hack and play with. It sure is one of my favourite VFD clocks so far!

Links

• Akafugu on Tindle
• Akafugu main site
• Code at GitHub

NumiQueen Review

€179 Kit without tubes, including case and power supply, €398 Kit with tubes (+ €5.50 for shipping outside of Germany) 

This is my first Numitron clock, and frankly I'm entirely taken by the elegance and clean lines of the digits presented by Numitron tubes. Probably the whole of the rest of the world already knows about Numitrons, and I'm the last person on earth to discover them, but all the same I'm happy it happened late rather then never.

Numitrons are the seven segment technology from before the time that LEDs became ubiquitous. LEDs were so cheap and robust, and made so few demands on the driving circuitry that they killed everything that came before. This stopped the production of tubes like Numitrons, and nowadays they are becoming increasingly rare and difficult to find. Even rarer are the tubes used in the "NumiQueen", the IV-13 tube, the so called queen of Numitrons. Nixies seem to be still fairly easy to come by in comparison, but Numitrons are the much exotic (and some say more beautiful) cousin. The IV-13's used in the NumiQueen are the largest and most beautiful examples of the already beautiful Numitron.

The technology itself is fairly simple: A filament s driven until it glows red hot in a vacuum, much like an under powered light bulb. Modern filament lamps with a retro look are based on the same idea: A filament glowing warm orange in a vacuum will last for a long time, provided that you run them in the correct way. If you drive them too hard, they can age quickly, and drive them too softly, and they will not glow correctly.

This is the innovation that the NumiQueen brings: The filaments are driven using a regulated constant current driver, meaning that manufacturing tolerances of each filament are rendered insignificant. The problem with driving tube filaments with an unregulated, or even regulated constant voltage driver is that the  circuit will place some filaments under stress because they have a lower resistance, leading to a higher current in that filament and shorter overall tube life. The NumiQueen manages the drive current (not the voltage), and therefore adapts the drive voltage to provide the correct current.

Back in the days of tungsten filament light bulbs, you may remember that they usually broke when the light was first turned on, and this is due to the inrush current at the moment of turning the light on while the filament is cold: tungsten filaments have a positive temperature coefficient, and the initial current drawn when the light turns on is higher than during normal usage, because the filament has not reached operating temperate and its resistance is low. After a few milliseconds, the filament heats up and the current falls. However, the inrush current at the moment of turning on is stressful for the filament. Constant current sources don't have this problem: The current reaches the limit level and the filament has time to heat up without being stressed.

Additionally to the current limiting circuitry, the NumiQueen has another trick up it's sleeve: The filaments are pre-heated with a low current before turning them on fully. This further reduces the stress on the tubes.

 The NumiQueen does everything possible to preserve the life of these valuable and rare Numitrons. Just because so much emphasis has been given to this doesn't mean that you should worry too much about the life of the tubes: They have a rated life of 50,000 hours, which is about 6 years in constant use. The NumiQueen is clearly trying to extend this already long life by treating them as gently as possible.

I bought the tubes for about $30 dollars each, as the kit came without tubes (there is a kit option including tubes, but I preferred to source them myself), but had to look around to find someone able to sell me the tubes. If this is too much trouble for you, Jürgen at NixieKits can supply the kit with tubes, which means that you'll have an easier time of it.

Brian used to do a size comparison with a standard "Diet Coke" can, but for two reasons that standard device is going to have to be changed. First of all, I don't drink that crap, and secondly the cans where I live are a different size and shape to the ones that used to be used. Perhaps Brian can ship me the standard can that he's been using. I promise I'll only use it for the size comparison and I promise won't drink it. (That was not hard to promise). In the mean time, we'll just have to find another size comparison object.

 

The Clock itself

Here we see the clock built from the parts I received in the kit. As I said, I sourced my own IV-13 tubes. You can see the tiny filigree filaments that there are inside, arranged as a standard seven segment display. There is also a decimal point which you can see on the last digit. Each clock also has a serial number, which you can see on the bottom

The acrylic case is a nice touch as well. It allows you to finish the clock to be something that you can proudly show to others, without having to wait for a case or build one yourself. You can easily build this clock in an evening, right up to and including the case.

There is also a power supply in the kit package, with a plug suited to your country available by selecting the appropriate option on the NixieKits site. I chose the back lights that randomly change colour, so you can see that it looks a bit like a circus, but there are other, more sober options also available when you order.

Another feature that you can just make out in this light is the filament pre-heating. You can see the faint glow of the filaments which are not lit up. This is the controller making sure that they are ready to go without the risk of giving them a thermal shock. This is a great feature and really shows the attention to detail.

 

Kit Construction

There is a separate article about the process of constructing the kit. However it suffices to say that the construction is not particularly difficult, and no special tools are required. Construction time is about 3 hours if you are moderately experienced.

The kit comes complete with a power adapter and a neat and tidy acrylic case, which is a nice touch, meaning that you will have a presentable clock right away at the at the end of the build, which is highly satisfying.

 

Features

The NumiQueen offers a fairly standard set of features for a tube clock, and if you have previous experience of either a PV Electronics or a NixieKits clock, you will find no surprises here. The NumiQueen is a totally faithful translation of Nixie clock features into a Numitron clock. Normally the features of this firmware doesn't really excite me very much, but along with the Numitrons, it works very well. The Numitrons themselves become the talking point of this clock, not the stunts that the firmware can do.

There are all the normal features you would expect:

• 12/24 hour time mode
• A variety of date formats
• Battery (supercap) backed up real time clock
• Configurable "night mode" (auto dimming or blanking of the tubes during the hours you have configured as being at night)
• Configurable day blanking (auto blanking of the tubes on certain days)
• Very flexible DST configuration
• Quick change between DST on and off with a specialized button
• Many different options for using an external time provider module (DCF/MSF/WWVB, GPS or NWTS)
• Alarm with configurable snooze
• Temperature display and detector.

The clock has 4 buttons on it, meaning that setting is quite straight forward and logical. One of the buttons is used for turning DST on and off, another is used for managing the alarm, and the last two are used for setting the clock up.

I set up the clock to use an NWTS, and this was really quite easy.  Set option 12 to "4" (GPS module) and option 13 to "1" (9600 baud) and that was it. The unit acquired the time right away. I did have to play with the DST settings for a few minutes to make them right, with option 14 set to "0" no hours difference and option 16 set to "1" (add the hours). 

 

The Numitrons

I was impressed by the brightness and elegance of the Numitron tubes. It's the first time I have seen them in real life, and it is a learning experience with them. They fit tightly into the sockets on the board, and putting them in for the first time was quite stressful: The new sockets are tight, and the tubes look so fragile. By a process of "wiggling" them in, they fit snugly against the case and all work perfectly. The sockets are really nice, high quality items, but you need to spend some time getting them aligned on the board so that the tubes stand up straight.

In use, they emit some heat: This was worrying at first to someone more used to Nixie tubes, which tend to stay more or less cold, even after hours of use. However, this is normal, and they didn't get so warm that it really worried me. It wasn't clar how much of the heat came from the tubes themselves, and how much came from the driver circuitry.

 

Time Keeping

The time keeping of the clock is of course excellent, especially with the addition of the nwts which is already in my collection, and which seems to work with pretty much everything. The time seems to be consistently up to 1 second out, but the time drift does not get worse over time when using the nwts unit. 

Changing from and to DST is easy to do because there is a button and an indicator for it, but there must be a better way to achieve this in 2017. It seems somehow a bit perverse that a high tech time keeping device needs a human to intervene to tell it the time. Admittedly, it's definitely a first world sort of problem, but really? DST rules are being largely simplified, and we're not dealing with a space shot, so a second here or there is not going to kill anyone, but there must be a better way than this.

 

Summary

The NumiQueen is a great product. It is well presented, not that hard to build, gives a really professional looking result, right down to the case. The Numitrons are a bit hard to find, and moderately expensive (but not as expensive as large tubes), but any troubles finding them, and Jürgen can supply the tubes with the kit.

Do I like the NumiQueen? Well I guess that this is already clear: It is my favourite clock of the moment.

Would I recommend to buy it? Yes, if you are looking for something a bit different from the more of less run of the mill Nixie experience, then the NumiQueen is a great answer to that. It's a bit expensive, but it gives a result that is out of the ordinary.

 Links

• YouTube video
• NumiQueen on YouTube
• NumiQueen.htm at NixieKits.eu

PV Electronics Spectrum 18 Build Review

It's time to review one of the most popular Nixie kits around. The Spectrum from PV Electronics is one of the standards of Nixie Kit builders since it was launched. It supports large tubes, and in this review we're using IN-18 tubes, which are still quite easily available, but which are starting to reach quite high prices. Expect to pay around $50 per tube for them, so that means a clock with IN-18 tubes will set you back around $400 before you have a case. I paid around £85 for the kit, so that's a bit over $100 dollars at the current exchange rate. Cases are available, but I didn't get one. I probably still will, but that's a thing for another day.

I have never looked at the Spectrum 18 before getting the kit to review it. I was aware that it is large format tube clock, the PCB measures 280mm x 80mm, but had not looked at the circuitry in detail. The package arrived quickly, but slightly damaged. Fortunately, the contents of the package was not affected by the damage to the packaging.

The PCB appears to be of high quality, with gold-plated pads and matt back solder mask. Before starting, I did a quick check I found several problems. Contacted Pete and told him about this, and he immediately replaced the PCB free of charge, and no questions asked. That's service!

The build manual is excellent, with plenty of clear illustrations and explanations. It is clearly laid out and takes you step by step through the build. I intend to more or less blindly follow the manual for this build. Scanning what there is to be done, it does not seem a challenging kit at all. All the tricky parts seem to have been dealt with (for example, the high voltage power supply comes already assembled). Things like pull up resistors for the back light LEDs are supplied as 9-pin SIL resistor network arrays, so also they are easy to install.

With this review, I'll also take you through a couple of "gotchas" that you should avoid doing. I'm building it so that you can learn from my mistakes.

 

Talking to Pete about the design decisions he made assures me that this is a clock intended for a long life. First of all, the tubes are already long-life doped tubes, secondly, the IN-18 tube seems to appreciate being used in a "direct-drive" clock. This means that the tubes are not rapidly multiplexed (switched on and off), and instead each digit element is supplied with a constant voltage, but at a lower current. Multiplexed clocks, although simpler, drive one tube at a time, and to achieve the brightness, each tube must be supplied with more instantaneous current. The average current remains the same, but the dreaded blue dot can appear in cases where the drive current is not exactly right.

Also the fact that tubes are socketed shows that this is a maintainable, high quality clock. One word of warning here though: Even if the tubes are socketed, refrain as much as possible from plugging and unplugging the tubes: the tubes are fragile, and the strain put on the pins during insertion and removal can cause out-gassing, which means the end of the tube. You should unplug and replug tubes only for valid reasons, such as replacing a damaged tube for good.

The High Voltage generator board is a separate board for the simple reason that if any part of the electronics needs replacing, it will be this part. The high voltage generator circuit gets hot and each time there is heat, the life of an electronic component is reduced. The rest of the circuitry is not under strain at all, and can be expected to last indefinitely. Having said this, even the HV board almost never fails, but if it does, it is a 2 minute job to change it.

Tube Holders & Resistor Networks (section 4.1 - 4.3)

The tube holders are acrylic mounting boards which diffuse the light of the RGB LED underneath the tube and also serve to hold the pins in place. Taking the covering off the acrylic can be a bit tricky, but rubbing the foil hard with a thumb can cause it to release easily. There is only one thing you have to be careful about with the tube holders, and that is to make sure you insert the pins from the right side and with the pin jaws pushed into the acrylic first.

Some of the holes are too big to take the pins, and this is intended. Not all of the pins on the IN-18 need to be used, and the larger holes are to remind you that the pin does not need to go in that hole.

Next you have to put the resistor networks onto the board. Make sure you do this from the bottom side of the board! If you do it from the top side of the board, the resistor network packages foul the tube holders and it gives an ugly result. In general, look for the silk screen marking that should guide you which side to mount components from. In this case, the silk screen rectangle is on the bottom side of the board.

The long SIL (Single In Line) packages for the resistor networks are not polarised, so you can put them in either way round.

Next you can put the tube holders onto the board. These should be mounted from the other side to the resistor networks, so, from the top of the board. The "notch" in the acrylic holder has to go near where the RGB LEDs pins go,

Low Voltage Supply (Section 4.4 . 4.5)

The low voltage power supply is a run of the mill buck regulator circuit using an LM2576. This has the advantage that it does not dissipate a lot of energy, and therefore increases the efficiency of the clock. The circuit is extremely straightforward and is taken almost directly from the data sheet:

 

 The only modification is that the input and output smoothing capacitors have slightly different values, and the Schottky diode is a generic 1N5819 instead of the 1N5822.

The capacitors and the regulator are laid down to reduce the profile of the board. You have to be careful to mount the capacitors with the correct polarity: make sure that the white stripe on the capacitor matches the markings on the board.

 The inductance and the socket are mounted on the bottom of the board.

Testing the low voltage circuit is easy. Power on the board, by connecting the power and check that nothing gets hot. After a few seconds if nothing gets hot, you can test the voltage at the test points on the top of the board. The test points are conveniently located on the top of the board, and are clearly marked.

 

High Voltage Supply (section 4.6 - 4.7)

The high voltage supply is usually the hardest part of a clock to build, but PV Electronics has taken a good route for the Spectrum: Instead of having individual components on the board to make the high voltage generator, the high voltage is generated by a pre-built and tested module. From one point of view, I think this is a clever move. If any part of the clock is going to wear out, it is going to be the high voltage generator: it gets hot and does a tough task, and for sure doing it this way means that there are less support calls. On the other hand I feel that part of the fun has been taken away. I'm sure it is not the general feeling that people will have.

The high voltage generation is therefore much easier to build than on a traditional clock. It only takes a few minutes, and if I understand the circuit correctly, the controller only needs to be installed to turn the generator on via he module's "enable" line. 

Tube Drive Circuit (section 4.8)

The tube drive circuit is made up of two HV5622 specialised controller ICs, which are purpose designed for driving high voltage circuits. The are 32 bit shift registers, with 32 output drivers capable of easily driving Nixies. They are quite easy to control, and in total there are 64 outputs. These are arranged as 6 x 10 outputs (for the tube cathodes) plus 2 x 2 further high voltage drivers for the separator neons.

The HV5622 appears to be running out of specification: The data sheet says that the supply voltage should be 10.8V - 13.2V, of course meaning that 12V is the ideal voltage, but in the Spectrum, it is being run at 5V. This rather neatly gets around a interfacing problem with the logic levels that the PIC controller can supply. If you had the HV5622 running from 12V, normally the defined logic levels should be that LOW is less than 2V, and HIGH is greater than 10V (which is vcc - 2V). Running the 5622 out of spec, makes the login interfacing easy, but it is outppf spec. I suppose here that he PIC can't drive the 5622 at anything near the 8MHz data rate, and this makes the combination reliable at 5V.

The only other point to note is that the sockets for the PLCC packages have to be put in the right way round, with the notch on the socket matching the notch marked on the silk screen. Get this wrong and you will suffer a lot.

Crystal (section 4.9)

The PIC controller has a great feature that Atmel controllers don't: they have an on-board Real Time Clock circuit (RTC) which only needs an external 32.768kHz crystal to make it work. The controller processor clock is then derived from this using a PLL. This part of the circuit is really easy.

Testing the Tubes (section 4.10)

While I like the idea of having the IN-18 tubes socketed (there is really no alternative), I'm not a huge fan of the sockets on the Spectrum 18. I had to fiddle about with them for a long time, and to my (rather conservative) tastes, they grip the pins on the tubes a bit too well. I know that a good connection is important, but these fragile old tubes don't like to be forced to do anything. They might not fail right away, but I always get the feeling that it is so easy to damage the tubes in the process of forcing them into the sockets.

I do see the need to have the acrylic holders, so that the pins don't get out of alignment, but I get the feeling that they constrict the pins a bit, meaning that excessive force might be necessary. I have no proof for this assertion, it's just a feeling I get.

Various Resistors (Section 4.11) and drivers (section 4.12)

These two sections of the manual deal with filling in some of the discrete components that are used in the clock. R8 - R11 are ballast resistors used on the neon indicators. R12 - R14 are current limiting resistors for the LED indicators, R17 - R19 are used for the speaker. R16 is a pull up resistor for the temperature sensor and R20 appears to be a total waste of time.

The drivers are the Q1, which is an MPSA42, which drives the speaker. This is a high voltage transistor, but I suppose it was chosen because it can withstand the voltages used in Nixie tubes, and the MPSA42 is being used here as a jelly-bean NPN transistor. Q2 - Q4 are used to drive the three channels of the RGB backlights.

Super Cap (Section 4.13)

C5 and C6 are a super capacitor and a decoupling capacitor, as well as a header to allow the board to be quickly reset. This circuit allows the clock to keep running which the power is turned off for a limited period of time. This means that the clock does not immediately forget the time. 

LEDs, Buttons and connectors (Section 4.14)

This section of the manual deals with installing the LEDs (D4 to indicate if the alarm is active, D5 to indicate if GPS module is active, D6 to indicate that Daylight Savings Time is on), the switches and the connectors the for external PIR and GPS/DCF module). I decided to install the LEDs standing upright, because I didn't want them protruding over the edge of the board, btu then found out that the switches protrude anyway. Depending on the sort of case you install, you might need to install some of these components on the botton of the board, so read the manual carefully!  

Buzzer (Section 4.15)

Well, that didn't take long! The buzzer is installed on the bottom of the board. I can't really find anything else to say about it.

RGB LEDs (Section 4.16)

Up until now, the clock has seemed to be a really well-designed and thought out kit, but this step feels a bit "how you doing" in comparison. The installation of the RGB LEDs is fiddly, hard to get right, and unnecessarily troublesome. The bending of the leads is a bit approximate, and you need to pay good attention to the orientation of the LED when you start bending the leads. In my kit, I had a spare RGB LED, and I suppose that this is because lots of people get at least one wrong. If you don't pay good attention to the way up you hold the LED when you start bending, it comes out with the common lead in the wrong position. Take good care!

Soldering the LEDs is also a bit awkward. The leads to be trimmed are difficult to trim, even wth tiny side cutters.

In the end, soldering the LEDs happened without any great mishaps, but I would have hoped for a better solution than what was offered. 

Temperature sensor (Section 4.17)

 Well, that didn't take long.

The neon separators (Section 4.18)

This is a fiddly task, and while going through it, I found that the manual is wrong. It says to cut the heat shrink sleeving for the neons with the long legs to 45mm, but that is too long for the glass tubes that are supplied. Instead I cut them to 40mm and that turned out just perfect. I also shrank the heat shrink sleeving before the final soldering, so that the heat of the soldering would not cause the extensions to drop off.

 

Final test

After installing the separators, I gave the clock a quick test. My tubes have cathode poisoning, and I'll show you in a later article how to deal with that, and also give the clock a full user review. 

Conclusions

I'm totally satisfied with the resulting clock. The Spectrum 18 kit is easy to build, and works well. The instructions are clear where they need to be, and short enough when there is no need for additional explanation. There are no complicated components to deal with, and as an overall impression, the kit is well worth the money. It has a good set of features, and is well thought through.

There are a few parts of the construction that don't match the overall quality of the rest of the kit. The tube holders don't fill me with confidence, and I feel that they are a bit brutal with the delicate and expensive IN-18 tubes. The mounting of the RGB LEDs feels a bit improvised, and a jig or on board LEDs might be a great addition to the kit. The leg extensions on the neons is a bit fiddly, and seems also a bit improvised.

However, these are minor niggles, and on the whole, the kit is excellent! I would recommend it to anyone wanting a large tube clock. 

 

 

Millclock IN-12 Walnut

Price $164.99, including shipping

Manufacturer: Millclock

Millclock are based in Ukraine and offer a range of assembled clocks and thermometers, as well as some kits. We're going to focus on an assembled clock in this review, which is one of the more simple clocks available from Millclock.

One point before we start about the kits: There's been some negative press about the kits, but you should take that with a pinch of salt; The complaints were that the assembly was difficult because the components used are SMD (Surface Mount Devices), but that's entirely clear from looking at the pictures on the site. The complaints are a little unfair, and the Millclock site states that there is some assembly skill needed.

However, we're talking about a fully assembled and tested item in this review: The IN-12 Nixie Tube Clock With Walnut Wood Enclosure.

 

 

Ordering, delivery, unboxing

The package arrived quickly from the Ukraine; the shipping costs part of the price, and the priority postage that Millclock uses means that you won't have to wait very long for the clock to arrive. The clock itself was well packed and in perfect condition, well padded with polystyrene against the worst that a postal service can do. Inside the box, there was a power supply, the clock unit, and a very short instruction sheet, which covered half a side of paper. Clearly there isn't a lot to configure in this clock.

A 12V 1A power supply with a EU plug on it was in the box, and all you need to do to get the clock going is to plug it in and set the time! Very easy indeed.

 

Overall impressions

The clock is very small, and is quite a triumph of miniaturization. The front panel is barely larger than the 4 IN-12 tubes, and the depth of the unit front to back is slightly larger than the height. There are two buttons on the top of the case, and a small hole in the top. This is for cooling on the pre-production unit, but will be removed for the mass production, because the clock does not produce very much heat. 

The case is entirely in wood, and nicely finished, with an etched logo on the back panel, which  is a nice touch. The rounded corners and the grain of the wood give the clock a nice feel. The unit is comfortingly heavy in the hand. In the front between the hours and the minutes, there is a single small neon indicator.

The unit measures 113mm wide, 44mm high and 44mm deep, and weighs about 160g. The new international Nixie measurement standard of a 100g Toblerone, which is 210mm, so that means that it's just over 0.5T wide in the new units.

There were a couple of slight problems in the final assembly of the case, but I think there are because the unit I have is an early pre-production model. They are not very serious problems: The back panel is glued on, and it does not look to be easy to change the battery. Some screws would have been a better solution, because eventually the battery will need to be replaced.

Also, on the review unit, the power lead is very short, it is only xx cm, and this means it's sometimes difficult to find a good location for the clock close enough to a power outlet. The power adaptor is glued directly into the case, and it's not possible to change it. The application of the glue was not very pretty.

Operation of the clock is quite straightforward, justifying the single page of instructions. It covers all the normal functions of a small clock. You can set the time and date, you can set the time format to 12 hour or 24 hour mode, you can turn on or off the back light, and you can set whether you want to have the date displayed. It's that simple!

Clearly, inside this clock there is a small SMD PCB which holds the electronics and the tubes. Measuring an IN-12 against the unit we can see that it looks like the tubes are mounted directly on the board, and that is not going to leave much room for electronics. My statement about the miniaturization seems to be true. 

 

 Operation

The operation is super simple, and it's perfect for a small, easy "fit and forget" clock that you might keep in an office or a bedroom. The left hand button is the "menu" button, to move between menus when you are setting the clock, and the right hand button, adjusts the setting, or shows the date when you are in normal time mode. Each time the date is shown, the display does a little scroll through animation, which also serves as a rudimentary anti cathode poisoning.

The menu is easy to understand. First press the "menu" button (the left one), and the neon stops flashing. This is an indication that you are in setting mode. Then you can press the "adjust" button (the right one) to change the settings. After you have set the hour, press the "menu" button again to move onto the minutes, and again you can press the "adjust" button to set the minutes. When you move onto the minutes, the neon stays on. This is the clock's way of telling you that you are in setting mode, and you are working on the right hand pair of digits, in this case, the minutes.

Pressing the "menu" button again takes you into the date settings. The neon is off, so we are working on the first two digits, which is the day of the month. Set this, and then press the "menu" button again, and the neon shows us that we are looking at the right hand digits, which is the month.

Press the "menu" button again, and now we move onto the year. The next option is the 12 hour or 24 hour mode. "00" means we are in 24 hour mode, which is the default, and "01" is 12 hour mode.

The next pair of options is the back light which can be "01", meaning back light on, which is the default, or "00" meaning back light off. It would be nice if the back light was turned on or off when you change the setting, but it only sets the back light LEDs once you exit the settings mode. The next setting is whether to show the date by default. This means that every so often the date will be shown automatically. "01" means show the date (the default) and "00" means do not show the date.

You will notice that there is no option to set the seconds, because this is done automatically when you exit settings mode. When you finish the setting up, the seconds are set to "00" automatically. 

IN-12 tubes are super robust, so the anti cathode poisoning isn't really that necessary.

The time is battery backed, meaning that if you turn it off, it still keeps time perfectly. It's not using something like a super-capacitor, which will keep the time for a few minutes, it has a battery so that it will keep counting time as long as the battery runs, and the life of these batteries is usually measured in years. Millclock tell me that the life of the battery is rated as 10 years.

 

Conclusion

This is an excellent tiny little clock, pretty much the smallest enclosed clock that you can make with the hardy IN-12 tubes. It doesn't have a lot of functions, but the ones it has are dead easy to use, and cover what you want for a clock in an office or a bedroom. It has all the beauty of Nixies, in a small, modern package, with a high quality case. I think it's a little pricey for what it is, but bear in mind that the cost includes priority shipping and some high quality materials.

There are one or two little finishing touches which it would be nice to take care of (the glued back to the case and the missing strain relief around the short cable), but apart from that, it's a high quality, uncomplicated, accurate clock.

There is also a "dark chocolate" version available.

The guarantee is 1 year.

All in all, a nice little clock. 

 

Bonus

There is also a tear down of the clock. Bear in mind that this is a pre-production version of the clock, and the electronics looks pretty complete, but there are a few little rough edges in the case and construction. The teardown video is here:

Links

• Millclock Walnut 4 digit mini clock
• Millclock "Dark Chocolate" 4 digit mini clock (alternative)
• Millclock main site
• YouTube video
• YouTube teardown video