Nixie Clock ITS1A User manual

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ITS1A CLOCK
ITS1A Clock

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Contents
Safety.......................................................................................................................................................... 4
Introduction................................................................................................................................................ 4
Bill of Materials........................................................................................................................................... 4
Main Board ................................................................................................................................................. 5
Diodes..................................................................................................................................................... 5
Resistors.................................................................................................................................................. 6
Zener Diodes........................................................................................................................................... 6
M1........................................................................................................................................................... 6
J3............................................................................................................................................................. 8
Ceramic Capacitors ................................................................................................................................. 8
IC1 Socket ............................................................................................................................................... 8
Transistors .............................................................................................................................................. 9
Programming Header.............................................................................................................................. 9
Reset Button ........................................................................................................................................... 9
ESP-01 Socket ......................................................................................................................................... 9
Inductor ................................................................................................................................................ 10
Electrolytic Capacitors .......................................................................................................................... 10
Power Test................................................................................................................................................ 10
Voltage Regulator ................................................................................................................................. 11
Display Header and Connector ................................................................................................................. 12
Connectors............................................................................................................................................ 12
Resistors................................................................................................................................................ 14
Check the Tubes.................................................................................................................................... 14
Solder the Tubes ....................................................................................................................................... 15
Colon LEDs ............................................................................................................................................ 17
Final Assembly .......................................................................................................................................... 17
Final Assembly ...................................................................................................................................... 17
The Moment of Truth ............................................................................................................................... 18
Initial Configuration .............................................................................................................................. 19

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Configuration............................................................................................................................................ 20
Presets .................................................................................................................................................. 20
Alexa ..................................................................................................................................................... 21
Backlighting and Underlighting................................................................................................................. 21
Motion Sensor .......................................................................................................................................... 23
Appendix A –PCB...................................................................................................................................... 24
Appendix B –Schematic............................................................................................................................ 26

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Safety
This is a kit of parts, not a finished item. The person assembling this kit must be familiar with the design
of these specific PCBs and with the assembly of electronics in general, including but not limited to: being
able to identify components, their location on the board and being qualified in the use of assembly
equipment such as soldering irons and other tools and being able to determine the correct and safe
functioning of this kit.
Any ‘instructions’ provided with this kit are guidelines only, and the assembler must be qualified to
determine the correctness, or not, of those instructions. If they have any concerns about the correct
functioning of the kit once assembled, they must cease all work and proceed no further.
No case is provided with this kit, the assembler must provide their own case.
The completed PCB (ITS1A Clock Kit) generates voltage differences of up to 450V between certain parts
of the PCB. THESE VOLTAGES MAY BE LETHAL. Therefore assembly should only be undertaken by people
qualified to work with these voltages, and who can guarantee that the completed product meets all
local safety requirements and certifications during operation. Furthermore, the finished article must be
in a casing that isolates people from access to these voltages during operation.
Certain parts of the PCB may maintain high voltage after it is unplugged from a power source, therefore
care must be taken to ensure that these voltages are not present prior to accessing the contents of the
case.
Introduction
Read through all of these instructions before starting. If, after doing so, you are not sure about your
ability to safely assemble this board, stop now.
Check that you have all the parts listed in the Bill of Materials.
Bill of Materials
Main Board
D1-D18
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DIODE GEN PURP 100V 200MA DO35
Z1
1
DIODE ZENER 3.2A 39V DO35
Z2, Z5
2
DIODE ZENER 100V 500MW DO35
Z3, Z4 - 2%
1
DIODE ZENER 75V 500MW DO35
R4
1
RES 12K OHM 1/4W 5% CF MINI
R2
1
RES 180 OHM 1/2W 5% CF MINI
R8
1
RES 6.2K OHM 1/4W 5% CF MINI
R7
1
RES 3.9K OHM 1/4W 5% CF MINI
R3, R1
2
RES 470K OHM 1/4W 5% CF MINI
R6, R17, R18
3
RES 1 OHM 1/8W 5% CF AXIAL
R5, R13, R14
3
RES 10K OHM 1/4W 5% CF MINI
R11, R12
2
RES 100K OHM 1/4W 5% CF MINI
R10, R15, R16
3
RES 1M OHM 1/4W 5% CF MINI
R9
1
RES 10M OHM 1/8W 5% CF AXIAL

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Q1
1
TRANS PNP 300V 0.5A TO-92, MPSA92
Q2
1
TRANS NPN 300V 0.5A TO-92, KSP42
L1
1
FIXED IND 220UH 640MA 450 MOHM
C1
1
CAP CER 0.22UF 100V X7R RADIAL
C2-C17,C20-C21
18
CAP ALUM 1UF 20% 100V RADIAL
C18
1
CAP ALUM 220UF 20% 10V RADIAL
C19
1
CAP CER 1000PF 50V C0G RADIAL
C22
1
CAP CER 100PF 50V NP0 RADIAL
C23
1
CAP CER 0.1UF 25V Y5V RADIAL
IC1
1
IC I/O EXPANDER I2C 16B 28SDIP, MCP23017
J3
1
MINI USB,RCPT, R/A, DIP, B TYPE,
U1
1
IC REG LINEAR 3.3V 500MA TO220-3, TC1262
U2
1
ESP-01
U2 Socket
1
ESP-01 SOCKET 8POS
S1
1
SWITCH TACTILE SPST-NO 0.05A 12V
Brackets
2
BRACKET UNIVERSAL CLEAR HOLE
IC1 Socket
1
CONN IC DIP SOCKET 28POS TIN
M1
1
IC REG BCK BST INV ADJ 1.5A 8DIP, MC33063
J2
1
CONN HEADER .100" DUAL R/A 8POS
J1
1
CONN HEADER FMALE 20POS .1" GOLD
6
MACH SCREW PAN HEAD SLOTTED M3
2
HEX NUT 0.217" M3
6
WASHER SPLIT LOCK M3 STEEL
4
HEX STANDOFF M3 BRASS 18MM
Display Board
Display board: R1, R2, R3,
R4
4
RES 47K OHM 1/4W 5% CF MINI
LED1-4
4
LED GREEN DIFFUSED ICE CUBE T/H
J1
1
CONN HEADER .100" SNGL R/A 20POS
Main Board
Please note that some of the pictures are from a previous revision of the board. This revision includes
additional resistors in a few places. This is nothing to worry about.
In addition, you may see some pictures with the USB connector on the bottom of the board. In this
revision the USB connector goes on the top of the board.
Diodes
Diodes are polarized. The end with the band should line up with the band on the symbol on the PCB (or
the lead on that end should go through the square hole). Note that all of these diodes (D1-D18) are the
ones that are loose in the bag. They do not have paper tabs attached to them.

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Start by soldering D1, Then D2-D13 as shown in the picture below. Use some tape to hold them all in
place while you do it. Note that the diode direction alternates as in the picture below. It is important
you get this right!
Follow up with D14-D17 (again, note that the polarity alternates), and finally D18.
That is all the regular diodes!
Resistors
Solder in all the marked resistors: R1-R18. Note that R2 is bigger than the others –bend the leads close
to the body. Also note that there are two sets of resistors marked R1-R4. The ones that are all the same
value are for the display board, not this board –those will have LED written on the paper strip.
Zener Diodes
Solder in the Zener diodes. Z1-Z5 Again, pay attention to the polarity. There are a mix of Zener voltages,
so make sure you solder the right ones. All of the Zener diodes have paper tabs attached to the leads.
The loose diodes are regular diodes that you should have already soldered in.
M1
Solder in M1. Check the polarity: The pin 1 marker should be near the L1 footprint as in this picture:

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J3
Solder in J3 –the Mini USB socket. Not all the pins need to be soldered –there is no data connection.
This should go on the top side of the board like this:
Ceramic Capacitors
Solder in the ceramic capacitors C1, C19, C22 and C23.
IC1 Socket
Solder in the IC1 socket. The notch should point towards the back of the board:

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Transistors
Solder in Q1 and Q2. Bend the leads beforehand to match the hole layout on the board. Make sure you
put the right transistor in the right holes!
Programming Header
If you think you might want to program the clock with the ESP-01 in place, solder in the programming
header J2. However I have found that most programmers don’t work through this:
Reset Button
Solder in the reset button as below:
ESP-01 Socket
If you want to be able to remove the ESP-01 (for example to program it in an external programmer)
solder in the 4x2 ESP-01 header. I would recommend this:

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Inductor
Solder in L1, the inductor.
Electrolytic Capacitors
Electrolytic capacitors are polarized. The negative lead must go in the negative hole and the positive
lead in the positive hole. The capacitors have a white stripe on the negative side, this should be lined up
with the white marking on the PCB footprint –the lead on that side should go through the round hole.
Solder in C18, this is the 220uF capacitor next to M1.
Solder in C2-C13. All of the stripes will face the same way. One technique to get them to line up nicely is
to use tape along the tops to hold them in place.
Solder in C14-C17. All of the stripes will face the same way, but this will be the opposite way of C2-C13.
Solder in C20 and C21.
Power Test
You can test the power now. You need to do this test before you solder in the voltage regulator. Once
that is in, the power supply will be disabled unless the EPS-01 enables it. As mentioned at the beginning
of this document: This PCB generates very high voltages that may be lethal. Furthermore, it can take
several minutes for those voltages to drop to safe levels after power has been removed because of
charged capacitors.

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It is beyond the scope of this document to suggest ways of troubleshooting any problems.
Plug a Mini USB cable into the USB socket on the PCB. Plug the other end into a USB power supply.
Unplug it if you see smoke!
Test the voltages in the following order. If any step fails the test, do not continue with the other tests.
Instead trouble-shoot and fix the voltage that is incorrect before proceeding.
1. Measure the 5V test point.
2. Now check the voltage at the 50V test point. This should be around 45V (50V was optimistic).
3. Check the voltage at the 150V test point. It should be around 135V (i.e. 3x45V)
4. Check the voltage at the 100V R test point (not the 100V test point –note the R). It should be
around 100V ± 5V.
5. Check the voltage at the -300V test point. It should be around -270V (i.e. 6x45V).
6. Check the voltage at the -250V R test point (not the -250V test point –note the R). It should be
around -250V ± 8V.
Unplug the power supply. Monitor the voltage on the 150V test point. The 1MΩbleeder resistor should
drain the 150V arm within a second. Monitor the voltage on the -300V check point (you will install a
bleeder resistor for this later). Only proceed once this has dropped to a safe level (e.g. <40V). You can
short it to GND to speed up the process, but this can cause sparks to fly!
Voltage Regulator
After this is soldered in, the HV power will be disabled until the ESP-01 is plugged in and enables it, so
you must perform the power test before doing this.
Solder in U1. This needs to be in the correct orientation. Use the photo below as a reference. You can
bend the legs so that it lays flat on the PCB as shown in the photo below:
Plug the power back in and check that you get 3.3V at the 3V3 test point.

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Display Header and Connector
This is a picture of the front of the display board. This is the side the tubes will be visible from.
Connectors
It connects at right-angles to the main board. A 1x20 socket is soldered to the main board, and a 20-pin
right-angled header is soldered to the display board. The two are held together using right-angled
brackets:
This is one way to make sure that everything lines up, when the socket and header are soldered in place:
1. Install the brackets on the main board.

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2. Insert the 1x20 socket into the main board, but do not solder it in place:
3. Insert the 1x20 right-angled header in to the display board as in the picture below, but do not
solder (note that this is the back of the display board).
4. Insert the header+display board in to the socket on the main board:

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5. Secure the display board to the brackets with the nuts and bolts provide.
6. Solder the socket to the main board –making sure it is flush with the board.
7. Solder the right-angled header to the display board.
8. Un-bolt the display board and remove it for the following steps.
Resistors
Solder the 47K resistors (Display: R1-R4) into place. You can choose whether you want these on the
front or the back.
Check the Tubes
Before you solder in the tubes, you should check that they work. Removing a broken tube is not easy.
There are a couple of things that can be checked before they are soldered in.
The first is to check that there are no shorts between the pins.
The second is to check that the tubes contain neon. The easiest way to do this is to hold them next to a
plasma globe, or anything that generates a few KV. Plasma globes are fairly cheap these days. Check
Amazon, ebay, Walmart, a toy store, a party store etc. etc. If there is neon in the tube, you should see an
orange glow inside it like the image on the left. The image on the right is of a nixie tube with no neon in
it. There is no orange glow inside it:

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Solder the Tubes
There are holes in the display board that were intended to allow the nipple on the tube to pass through.
In fact, on the first tube I installed the nipple was at a sharp angle to the tube and did not line up with
the hole, so I ended up installing all the tubes so that the nipple did not go through the PCB. This turned
out pretty well, and meant that I didn’t have to straighten the leads on the tube all the way up to the
glass. In fact, I have heard reports that the leads of ITS1A/B tubes can sometimes snap off at or near the
glass, so you should avoid applying too much force in that vicinity anyway.
Once the leads are reasonably straight, starting with any lead you like, work around the tube and trim
each one slightly shorter than the last. This will make it easier to insert the leads in to the holes because
you only have to insert one lead at a time.
Now insert the leads into one end or the other of the display board, from the same side as the outlines.
You will notice that the tubes have two missing leads. These should match up with the missing holes on
the footprints. In other words, you can’t install the tubes upside-down!
In the next picture you can see the trimmed leads, and the nipple I was describing:

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Once you have all the leads inserted, you will notice that the tube is quite firmly held in place, however
line up the tube so that that it is sitting roughly square, then solder one of the leads.

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Next repeat this sequence at the other end of the display board. Now insert all of the rest of the tubes,
leaving them unsoldered.
Now you will want to try and get them as square as you can. This will take some trial and error. Here is
one suggested sequence:
1. Lay the assembly down on your work surface as in the picture below.
2. Adjust the two tubes on the ends until the board is level with the display surface. You could
make a jig to do this by cutting small pieces of material such as wood to hold the PCB at the
same height on all sides, or you could just keep re-soldering and measuring.
3. Once you are happy that the two end tubes are square and the PCB is level with the work
surface, adjust the remaining tubes and tack them in place with by soldering a single lead.
4. Eyeball the results. Do the tubes line up properly? If not, repeat the above steps.
5. When everything looks OK. Solder another lead in place opposite the previous lead. Check again.
6. If everything is still OK. Do another lead. Etc. etc.
7. Trim the leads flush with the back of the PCB!
Colon LEDs
LEDs are polarized components. The anode hole on the display board is marked with a little ‘+’ symbol.
The long lead of the LED will go in this hole.
Decide how far in you want to insert the LEDs, then solder them in place. At first, just solder one lead so
it is easy to rectify any mistakes.
Final Assembly
Final Assembly
Insert IC1 into its socket. For some reason that I will never understand, the pins on an IC never line up
with the holes in the socket. You will need to bend them slightly. Use whatever method you are

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comfortable with to do this. Make sure the chip is oriented correctly! The notch should be next to the
1x20 socket that the display board plugs in to –it is circled in the next picture.
Insert the ESP-01. Either solder it in place or insert it into the socket you soldered earlier.
Insert the display board into the socket on the main board. Bolt it in place.
Check the resistance between ground and the bottom pin of one of the tubes –this is the anode 2 pin –
it should be around 470k.
The Moment of Truth
Insert the USB lead into the socket on the main board, insert the other end into a USB adapter. If you
see smoke, unplug it!
The red LED on the ESP-01 should come on (if it has one, there are several variations of the ESP-01).
After a few moments, the tubes should display all ones. Then it will start counting up –with each tube
one ahead of the tube to its left. This is intended to test that all of the segments light up and extinguish
properly. In addition, the colon leds should blink on and off.
If not all segments light, or some segments stay lit when they shouldn’t don’t panic. First of all, leave it
running for a few minutes to see if it fixes itself. In fact, the datasheet recommends that if the tubes
haven’t been used for a month or more, you should run them for at least 10 minutes. They have
probably been unused for a lot longer than 1 month!
The -250V line is the key one that affects segment brightness and whether they come on or not. It can
sometimes take a few minutes to stabilize, and it can take the tubes a little while to warm up. Chances
are that any unlit segments will come on after a few minutes, provided the digits are changing –for
example when the date is displayed. If they still don’t come on after 10 minutes, check the -250V line –
it needs to be at least -235V.

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If segments stay on when they should go off, you can increase the Reset Pulse Length in the Extra config
screen. Generally you will want this value to be as low as possible as that will reduce flicker, but you also
want segments to go out!
Initial Configuration
All configuration of the clock is done via a web interface. The clock will publish a WiFi access point
whose name ends in ITS1AClock. Connect to it –the password is secretsauce. When you connect to it,
you should then be taken to a captive portal that will display this page:
•You can set the time on the clock right from this page. Hit the Set Clock Time button. It will set
the time to whatever the time is on your phone/PC. The clock should stop counting and display
the time. The display might go blank –this is because it is pre-configured to only be on between
6am and 10pm. You can change this in the main config screen:
•You can also configure the clock right from the captive portal. Hit the Configure Clock button!
•Configure WiFi and Configure WiFi (no Scan), allow you to connect the clock to a router. If you
do this the clock will synchronize time with a time server on the internet and you can configure
the clock by pointing a browser at http://its1aclock.local/. This page also allows you to rename
the clock, which will also rename the access point.

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Configuration
The clock is configured via a web browser, either from the captive portal (which is displayed when you
connect to the clock’s access point), or by connecting to http://its1a.local/ once you have connected the
clock to a router. Some browsers/routers don’t understand the .local domain. For these you will need
the IP address. You can get this by connecting to the clock’s access point and hitting the Info button. The
main config screen looks like this:
When the clock is connected to the internet via a router, it will synchronize with a time server at
http://time.nixies.us/getTime. You will need to know your timezone. There is a list here. The example in
the picture above is for Eastern Standard Time. The clock will automatically adjust for DST in the given
timezone.
You can access other settings by hitting the menu button at the top left (the three lines in a circle).
Any change you make will take immediate effect, but it won’t be saved to flash for up to 1 minute –i.e.
if you reset or power-cycle the clock before the changes are written to flash, the changes will be lost.
Presets
The clock allows you to store up to five presets –these are named collections of settings. You can access
the presets by hitting the menu button on the top-right of the screen –it is labelled with the currently
selected preset. 24 Hour in the picture above. The menu won’t go away unless you either select a
different preset, or use the main menu button.
Any change you make while a preset is selected, will be saved to that preset.