As noted in the title above, this is an optional part, you can safely skip it; here I'm just telling how this clock had come to life, what are the key differences from other DIY projects and some other, maybe less useful, but still interesting information.

My journey with the Nixie clocks started several years ago, when I bought some Z560M Nixie tubes for cheap and decided to make a clock using them. I checked commonly available circuits and designs but liked none of them - they all were either using the ancient SN74141 driver ICs, which have issues like uneven illumination or blue dots, and even worse, most of these circuits used multiplexing, which caused additional issues like ghosting, or they were Arduino or other monstrosity based. Therefore, I decided to build my own from the scratch. There were several prototypes built, and final model was based on combo of PIC16F887+DS1302+MPSA42 transistors. I made instructable for making your own copy and it was quite popular - there were even some minor mentions in mass media (And this was my first and so far - last post on Instagram to gather more than 1k likes). Many people then asked for improvement of circuitry, like using more precise DS3231 or adding some extra features. Due to various reasons, I shelved that project for indefinite time, but recently, when scrolling thru local flea market, I have noticed very interesting module, it was plastic bag with some tubes visible inside. Initially, I thought there were just vacuum tubes, but when I checked closely, these turned out to be 4 pcs of ZM1000R tubes and 1 pc. of ZM1001R tube. They were soldered to PCB along with dozen of other components, and bag containing that module was marked as "Afora spare #xxxx". They were asking $50 for the whole set, quick check on ebay showed that this was kind of offer that you won't encounter every day, so I immediately bought them and decided to make another nixie tube clock.

When I bought them home, I started thinking, what kind of clock design should I use? I really do not like steampunk/loft/Victorian/rococo and other designs, which have many fine details and "overloaded" designs - I prefer clean, spacious lines with overall styling from Mid Century Modern and Streamline Modern. Therefore, when designing this clock, I tried to maintain continuity while working on external styling of it - you can see characteristic materials, curves and shapes, which I already used in my previous model.

Vertical nixie tubes allow less flexibility in design - they have to be placed vertically, so most non-steampunk nixie clocks using tubes of similar style are just brick of wood with tubes sticking from the top. This is not exactly kind of design I enjoy, so I decided to add some air and dynamics to it, by placing tubes in semi-circle fashion and shaping enclosure accordingly, while maintaining continuity - the materials are exactly the same that I've used in my previous model - same mahogany wood from microscope case, same retro speaker cloth, same red acryllic. I decided to abandon brass inserts for this time, to ease manufacturing process, so there are no brass rings around tubes now, and logo also had to go (Actually, I had plans to make it from red acrylic, but it does not fits other components). As you can see from the pictures, there were several different prototypes built, until I come to final design.

I decided to name this clock “Satellite” – since it’s shape, when looked from above, can be roughly compared to a meteor, satellite, shooting star or any other interstellar object in motion.

Feature-wise, I made some major improvements in functionality - clock now has alarm, which can be set to be working only during the workdays. Also, there is automatic or manual brightness control, clock setup is done via two buttons instead of one, setup menu now is much simpler and intuitive, and there is even an option for precision time calibration, if needed.

There were number of significant improvements made to clock hardware too:

- Using DS3231 RTC instead of DS1302, for much precise timekeeping (and you can fine-tune it).

- RTC uses supercap for timekeeping in case of power loss, instead of the lithium battery.

- Number of components being used is significantly reduced. (Gone all 30 pcs of 10k resistors)

- Built-in PWM generator used for brightness control and alarm sound. (with possibility to play some polyphonic tunes in the future)

- High voltage supply now is integrated on the mainboard, no need for separate module any more.

- Main PCB is about 50% smaller than one used in the previous model.

All above has one disadvantage - PCB now is double sided and it uses SMD components, so making it at home won't be that easy, but there are various PCB manufacturers like JLCPCB or ExpressPCB, which will make 5 pcs of this PCB for about $4 - quite reasonable price in my opinion.

That is all, now let us go forward and make it!

Supplies

Below is the list of components and materials needed to build this Clock

4 pcs. of ZM1000 + 1 pcs. of ZM1001 nixie tube, or 4 pcs. of ZM1080+ 1 pcs. ZM1081 tube, or 4 pcs. IN14+IN19V or 4 pcs. IN12+IN15V (you have to design your own enclosure in this case, my design won't fit these tubes)

PIC186F887 IC - 1 pcs.

DIP40 IC socket - 1 pcs.

UC3843 IC (either in DIP-8 or SOIC-8 package) - 1 pcs.

DS3231 IC - 1 pcs.

MPSA42 transistors (TO-92 package) - 30 pcs.

78M05 voltage converter – 1 pcs.

UF4004 or any other ultrafast diode, rated at least 400V and 1A – 1 pcs.

High voltage MOSFET, rated at least 250V and 4A, like 4N60, 7N60, 20N60, 33N25 and so on.

3mm orange LEDs – 10 pcs.

5.5V Supercap with 0.1F or higher capacity. Amount of capacity determines backup time in case of mains power loss. By rough estimations, each 0.1F means extra 24 hours of backup. PCB design accommodates most common round and square 5.5v supercaps. I have tested some cheap, “CDA” branded 0.47F supercaps, which provided about 1 week of backup time. I also used 0.1F supercap from Tokin, which provided about 3 days of backup, so choose supercap according to your needs.

22k 1/4W resistors - 5 pcs.

470k 1/4W resistor - 1 pcs.

10k 1/4W or 1/6W resistors - 3 pcs.

220 ohm 1/4W or 1/6W resistors – 5 pcs.

5V passive buzzer - 1 pcs.

8mm pushbuttons – 2 pcs.

4 position rotary switch – 1 pcs.

2 position slide switch – 1 pcs

0.1uf 50V ceramic capacitor – 2 pcs.

220-560uf 25-35V electrolytic capacitor – 1 pcs. (LowESR type)

4.7-10uf 250-450v electrolytic capacitor – 1 pcs. (LowESR type)

100uh shielded inductor (12x12x7mm size) – 1 pcs

12V 0.5A (or higher) AC power supply.

SMD components (all should be 1206 size)

Any rectifier diode, (avoid schottky diodes) – 1 pcs (RS1M or similar)

1 ohm resistor - 2 pcs

10K resistor – 3 pcs

1K resistor – 1 pcs

6.8K resistor – 1 pcs

47K resistor – 1 pcs

150K resistor – 1 pcs

0.1uf capacitor - 2 pcs

1000pf (1nf) capacitor – 1 pcs (all capacitors should be X7R type and rated at 25V at least)

470pf capacitor – 1 pcs

100 pf capacitor – 1 pcs.

Raw materials:

Plywood sheet 3mm thickness (Approximately 30x30cm)

Plywood sheet 10mm thickness (Approximately 30x30cm)

Hardwood sheet 5mm thickness (Approximately 20x30cm)

Deep red or black 3mm acrylic sheet (Approximately 20x20cm)

Vintage style speaker cloth (Approximately 1 meters x15cm)

2 pcs. Brass pegs (available in DIY jewelry stores)

4 pcs. M3 brass standoffs.

4 pcs. Hex head M3 screws (20mm length)

6 pcs. M3 screws with flat/conical head.

5 pcs. ½ inch silicone o-rings

1 row (40pins) 20mm PCB to PCB connecting jumpers

Wood glue (optional)

Epoxy glue

Double sided adhesive tape (thin type)

Sandpaper of various grit (150-300-600-1200)

Wood wax paste

Tools and machinery:

CNC router, laser cutter (for logo making) pliers, screwdrivers, soldering iron, soldering paste, wires, etc.

Step 1: Assembling the Electronics

On the first picture, you can see the main PCB and its connections to “external world”. Most pins go to the “daughterboard”, but some of them are for connecting the buttons, switches and buzzer. Please note, the LED switch should be connected between the “motherboard” and “daughterboard”. All other parts are marked on the PCB, so you will have no issues finding which part to solder where. In case of difficulties, please refer to assembled PCB picture below. It is possible to use UC3843 either in DIP-8 or SOIC-8 package, so there are white dots on PCB for each option, showing the location if pin #1. Capacitors can be mounted at top or bottom of main PCB – there is no difference, it is just matter of taste.

“Daughterboard” is relatively simpler to assemble, just take caution not to overheat tube pins when soldering – while tubes are made from glass and have much higher tolerance to higher temperatures, compared to semiconductors, they still can fail, if you apply heat for too long. At the center of the daughterboard is a place for switch, which will be used to select the digit used for the middle separator. The PCB design allows to use all 6 digits available in ZM1001 tube, but as practice showed, letters “Z” and “Y” aren’t really great as middle separator, so I used only four of them – “~”, “X”, “-“, “+”.

The daughterboard also has LEDs soldered to it - they provide nice backlighting for the tube bottom. I've used 10pcs 3mm orange LEDs, but you can use any color you desire - some like blue, some like red, I liked orange color :) If you don't need backlighting, you can skip this step.

After daughterboard is assembled, place the silicone o-rings over their bottom part - they are used to center the clock PCB inside the enclosure and provide strain relief, since tubes are hard soldered to PCB, and they are expanding a bit while getting hot, so having extra cushioning around them, prevents them from possible cracking.

As I have noted above, since ZM1000/1001 tubes are quite rare and expensive, I have designed additional daughterboards, which allow to use much more common and cheap nixie tubes. Therefore, instead of ZM1000+ZM1001, you can use ZM1080 and ZM1081, IN14+IN19V, Dolam LC 531+ZM1081 and many other combos. Please note, since these tubes have flexible legs, I have included “one fits all” design PCB, so you have to map their legs to the appropriate holes by yourself. Also I’m including another PCB, which is designed for IN12+IN15V tubes, but since these tubes are facing upwards (you have to install them from the OPPOSITE side), the case design included in this instructable will be useless, so you have to either design your own, or wait until I design and build a new one, specially designed for that tube combo.

After the assembly, before installing the main chip, it will be wise if you check +5 volts and HV output, which should be around 180V. Also, check the current being consumed - without main IC and tubes connected, HV converter should draw no more than 0.02A. If all these are ok, you can install preprogrammed PIC16F887 into socket, connect the “mainboard” to “daughterboard”, and supply the power. Be careful with high voltage capacitor – depending on its quality, it can maintain charge for up to several hours, so you might get very unpleasant “zap” by carelessly touching HV parts.

For the power supply, you can use any wall-wart adapter, which can deliver 12 volt and at least 0.5A of current. I’ve used some bare module, for which I’ve made case out of colored acrylic (drawings for it are also included in the attached files)

Step 2: Making the Enclosure and Assembling the Clock

Clock enclosure consists from the following parts (from top to bottom)

1. Top panel (made from mahogany)

2. 3mm plywood part with holes for tubes

3. 10mm plywood part

4. 3mm ruby red acrylic insert

5. 10mm plywood part

6. 3mm plywood spacer

7. Bottom panel (Made from mahogany)

The parts #2 and #3 are glued together and coated with vintage speaker cloth. Parts #5 and 6 are also assembled in that fashion. Then, these parts, with part #4 in between are again glued together.

Parts #1 and #7 are made from the 5mm mahogany wood sheet. I've used Artcam 2018 to generate .TAP files (to be used with G-Code sender/Candle CNC. If you need them, tell me and I'll upload.

I've used double sided adhesive tape to glue the speaker cloth to the main frame parts, please refer to pictures for possible ways of doing it. You can also use pre-glued speaker cloth fabric, if such one is available in your area.

Flat screws are passed thru holes in top plywood sheet and glued in them with epoxy glue. The daughterboard is fixed to these screws with brass standoffs. Mainboard is plugged into daughterboard and soldered.

The bottom part was made from two piece just due to fact that wood I was using had a nasty hole in the center, so I had to cut a square hole and glue in insert, cut from the another piece of wood. I've laser engraved some text on it and used acrylic paint to fill in the cutout - it looks quite good.

Bottom part also holds the switch for backlight LED power on/off, digit selection switch (which is glued using plywood spacers) and two buttons.

Step 3: User Manual, Additional Information and File Downloads

This clock has two buttons, left button is used for the Settings menu and right button for adjusting the current item when in the settings menu. In normal mode, pressing the right button displays current year, month/day and alarm hours, if alarm is enabled (separator will blink rapidly to show you that alarm is enabled).

When you cycle thru the menu with left button, the digits at left show the menu item number, and digits on right - value of the current parameter, which can be altered with the right button. Please check the list below for all menu statements.

1 set year

2 set month

3 set date

4 set current day of week. 0 = Sunday (Needed for alarm functionality per weekends)

5 set hours

6 set minutes

7 set time display format. 12/24.

8 set alarm hours

9 set alarm minutes

10 set alarm. Alarm enable=1, enable only on workdays=2, disable=0

11 set time corrector value. 30 means no change, set values below 30 if clock is too fast, above - if it is slow

12 set display brightness

13 set display automatic (adjusted hourly) brightness, 0 off, 1 - on

14 exit

Please note, alarm and time hours are being set in 24 hour format, even if display format is set to 12 hours.

Clock circuitry had been fine tuned (about 12 different prototypes were built!) and there are no adjustments or modifications needed for it to work properly. The only relatively "critical" part is inductor. I've used most common, 12X12X7mm type, 100uH inductor. You can also use smaller, 10x10x4mm inductor, but current consumption (and heat produced) will be about 30% more. Small variations in inductance is acceptable, like you can use 82uh or 120uh instead of 100uh, but I suggest to avoid extreme changes, like using 47uh or 220uh inductors. Converter will work with them too, but efficiency will be low, amount of heat being produced - higher and it can lead to main MOSFET failure. And speaking of MOSFETs, there is absolutely no need to use high current transistors - ones rated for 20, 30, 50 amps - they have higher gate capacity, so converter chip will waste more power for no good reason. Another MOSFET selection guide is it's working voltage. Generally, as working voltage increases, voltage drop on open transistor also increases, which leads to additional power loss and heat generation. So if you can get 250V transistor, instead of 400 or 600V one, use it - there will be less heat generated, which is quite important, due to confined space inside the clock. Do not use 200V MOSFETs - they might work, but most likely, will fail shortly, so 250V transistor is the best selection in my opinion.

For the "Calibration" option, I added it because, there are many fake and used DS3231 sold online as new, and they either lag for couple of seconds, or go forward. With this option, you can adjust in -15 + 15 second range daily adjustment. as I've found during testing of various cheap DS3231, usually they lag behind, so setting corrector value to +2 solves that issue with ease.

List of files:

Firmware887.hex - firmware in HEX format, to be flashed using PICKIT or any other programmer.

Mainboard.rar - contains all gerber files required for making the main clock PCB.

ZM1000daughterboard.rar - contains gerber files for ZM 1000 Tube daughterboard.

DaughterboardIN12.rar - gerber files for daughterboard with IN12/IN 15V tubes.

DaughterboardALL.rar - gerber files for daughterboard with IN14/19, ZM1080, LC-531 and others.

Woodenparts.rar - files for wooden parts manufacturing, in .SVG format, K40 laser engraver ready.

Introduction: Mid Century Modern Nixie Clock (Mk2)

Supplies

Step 1: Assembling the Electronics

Step 2: Making the Enclosure and Assembling the Clock

Step 3: User Manual, Additional Information and File Downloads

Attachments