How do they do that?

[Jurek]

In here, as I cannot think of where else I might get an answer....
As mentioned elsewhere, my Nixie tube clock arrived from Ukraine a few days ago, and while I was in the process of emailing the vendor to ask for some instructions how to set the time, I realised that it was already showing the correct time, and date. Plug-in-and-play, effectively.
All very well, but how?
The thing runs off the mains via a wallwart, but I'm guessing it must have an internal power source (a battery) to keep the clock / calendar programmed. No?
However, what is properly doing my head in, is that the clock jumped an hour forward to BST since yesterday, without any intervention from me.
How can this be? Given that the date when this happens varies from one time zone to another across countries and, as I've said, I've not had to set anything on it regarding regions or times.
Can anyone 'splain?

[delthebike]

Radio controlled.
https://en.wikipedia.org/wiki/Radio_clock

[Kim]

If I was paying hundreds of pounds for a clock, I'd definitely want it to get its time from some external reference.  We can reasonably assume that it isn't using NTP because you haven't configured anything to connect it to a network.  Since it's from Russia, an MSF receiver seems unlikely, but not impossible.  You can count mains cycles to keep a clock accurate, but not via a DC wall-wart, and that doesn't actually tell you the time of day.

Has it got a GPS receiver^[1] in it?

Or it could just be that it's got a battery backed RTC, the seller was kind enough to set it to the right time for you, and it's able to calculate DST changes from the date (it's a reasonably simple algorithm for Europe, anyway).


_{[1] Although a GPS receiver just gives you GPS time.  You really need additional data to convert this to UTC and from there a local timezone.}

[Jurek]

Thanks both, that'd make sense - oddly enough some of the models from the same vendor were advertised as 'GPS enabled' -I wasn't aware that mine was one of them.

[pcolbeck]

RTC battery backed up almost certainly.
Europe is really easy to do summer and winter time for its just the last Sunday in March and the last Sunday in October.. I am always having to set that on network kit.
Lots of stuff has it built in these days as computers are so cheap. My boiler and cylinder controller for the central heating has it built in but annoyingly the hall thermostat/clock that controls when the radiators draw heat doesn't.

[Kim]

[Jurek]

Okee-dokee.
So I was right about the internal power source.
Comme ca:


So what is this? An aerial? The thing on the end looks very much like a transistor.

[David Martin]

Could be a 1-wire temperature sensor or similar. What are the markings on the ICs?

..d

[Jurek]

Could be a 1-wire temperature sensor or similar. What are the markings on the ICs?

..d

All 3 legs look to be connected.
Marked thusly:
DALLAS
18B20
1726C4
+760AA

ETA - That's not on the IC's  - That's on the tranny thing.

[David Martin]

18B20 is a temperature sensor 1-wire. Good stuff. So does the clock tell the temeprature too? I presume it is on the short wire to keep it away from the heat of the Nixies.

[Jurek]

18B20 is a temperature sensor 1-wire. Good stuff. So does the clock tell the temeprature too? I presume it is on the short wire to keep it away from the heat of the Nixies.

Not that I'm aware of, David - But TBH it appears to have more modes than I can shake a stick at....
So there's every chance that it might display local temp.

The four rectangular ICs are marked identically thus:
74HC595D
HYC23XO - That makes me guess that they're something to do with the backup battery
UnL1716P

The square IC is marked thus:
32FJOO
C8T6B
H22293
CHN320

You've no idea what a strain reading those was on my eyesight
And my loupe.

ETA - Thumbing through the *interestingly* translated instructions, it would appear that it does indeed have the capacity to display local temp.

[David Martin]

You will have one 74HC595 per tube. This takes a serial output and turns it into parallel for selecting which of the digits will be shown.
The square one is a C8t6B which is a fairly high powered microprocessor to be using for a clock.  I expect it tells the temperature and does a few other things as well. Looks like it had a buzzer on there too.

[Jurek]

You will have one 74HC595 per tube. This takes a serial output and turns it into parallel for selecting which of the digits will be shown.
The square one is a C8t6B which is a fairly high powered microprocessor to be using for a clock.  I expect it tells the temperature and does a few other things as well. Looks like it had a buzzer on there too.

So, questions...
I have 4 x 74HC595  but I have six tubes 
Yup there is a buzzer / piezo thing  on there - It buzzez once an hour.
I must investigate how to display room temp - but, as I've said, the destructions are *interesting*.

[David Martin]

some of the tubes only require a limited number of digits. E.g 0-5 or 0-2. You have a few extra options from the microprocessor as well. The four 74HC595 turn 4 outputs into 32.

[Jurek]

some of the tubes only require a limited number of digits. E.g 0-5 or 0-2. You have a few extra options from the microprocessor as well. The four 74HC595 turn 4 outputs into 32.

Thank you.
The 0-5 / 0-2 thing makes total sense.

[delthebike]

So what is this? An aerial? The thing on the end looks very much like a transistor.

It's the Anti Tamper Warranty Jack Transistor!   

[Jurek]

So what is this? An aerial? The thing on the end looks very much like a transistor.

It's the Anti Tamper Warranty Jack Transistor!   

That's me f*cked, then.
And the Ukrainians probably know where I am.

[Jurek]

I have to confess, interesting though this thread has been, I'm no closer to knowing how this clock knows when it should change from GMT to BST.
Radio?
GPS?
Witchcraft?
Anyone?
TIA

[pcolbeck]

In built clock chip (and these include the date and year as part of the time) with battery backup. The same chip has been programmed with the daylight saving time formula (ie last Sunday in March etc). So once it hits 1:00am on the last Sunday in March boom it switches to BST.

[Jurek]

Thanks Pat 

[Greenbank]

The square chip (C8T6B) is a 32-bit ARM CPU, more than enough clout to take the time/date from the battery-backed RTC (real time clock) and apply the various rules for DST switchover. If there is no GPS then it was probably programmed to follow UK rules based on delivery address.

Similar to this: https://www.aliexpress.com/item/Free-Shipping-20PCS-LOT-ST-32F100-C8T6B-MCU-32BIT-ARM-64K-FLASH-48LQFP-STM32F100C8T6B/32459706955.html

If there's another square chip marked A2035H then it's definitely GPS controlled, that's a very common GPS receiver. It could be located on the other side of the board (so it faces up) by the green headphone jack style socket (by the look of the through pins around there).

[Kim]

18B20 is a temperature sensor 1-wire. Good stuff. So does the clock tell the temeprature too? I presume it is on the short wire to keep it away from the heat of the Nixies.

IME those are a complete pain for over-reading if you put them on a PCB with anything remotely interesting (power regulators, microprocessors, power transistors, etc) on it, even if you keep the legs long and do strategic stuff with ground planes to keep all the heat on the other side of the board.  In the absence of fan-cooling so you can mount them in front of the intake, dangling out the back on a bit of wire is the best way to get a precise reading of ambient temperature.

12-bit resolution, accurate to 0.5C, prolific software support and they cost peanuts.  Lovely.   

[Diver300]

18B20 is a temperature sensor 1-wire. Good stuff. So does the clock tell the temeprature too? I presume it is on the short wire to keep it away from the heat of the Nixies.

IME those are a complete pain for over-reading if you put them on a PCB with anything remotely interesting (power regulators, microprocessors, power transistors, etc) on it, even if you keep the legs long and do strategic stuff with ground planes to keep all the heat on the other side of the board.  In the absence of fan-cooling so you can mount them in front of the intake, dangling out the back on a bit of wire is the best way to get a precise reading of ambient temperature.

12-bit resolution, accurate to 0.5C, prolific software support and they cost peanuts.  Lovely.   

And you can parallel multiple sensors, using normal wire, while reading each one individually. You do need some way to work out which is which.

[Greenbank]

If I ever get my flat rewired then I'll be including a 1-wire run through all rooms as well as cat-5 everywhere.

I still haven't got round to doing my temperature sensor stuff using 18B20 (and Honeywell humidity sensors). Rather than one long wire I was going to use Raspberry Pi Zeros which can do 1-wire gubbins. Heating was also going to be monitored by ziptie-ing a 18B20 to the incoming leg of a radiator in one of the rooms.

[Kim]

I still haven't got round to doing my temperature sensor stuff using 18B20 (and Honeywell humidity sensors). Rather than one long wire I was going to use Raspberry Pi Zeros which can do 1-wire gubbins.

That's more or less how I've done it (as a bonus feature of a Pi model B-based deaf alerting system).  I've used proper 1-wire transceiver chips (DS2482) hanging off the I²C interface, because that way it supports the full range of 1-wire devices (at the time the bit-bashed library only supported temperature sensors, it may have improved) and I could use OWFS to do the boring low-level stuff.