Build your own LCD clock with date and thermometer 

What makes you think that it need AC?

Can run on dc but with ac it will last long as far as I know

@@01Hudesohn because that’s how LCDs are driven, to prevent damage which is caused by extended application of DC. I forget what the exact mechanism of damage is, but AC is how we prevent it.

@@tookitogo AC prevents damage? The Clock runs on DC Batteries.

@@01Hudesohn the backplane on an lcd (same as the common pin on an led 7 segment) is driven by a uC pin with a square wave. The segments are driven by another pin at opposite phase so the lcd effectively sees an ac square wave voltage. If the segment is meant to be inactive, the pin drives it in phase so the effective voltage is 0v. He shows it on the oscilloscope near the end.

Exactly.

Dog has replaced the cat in this story :D

There are some other accurate time transmitters around the world. Look for "Radio clock" on wikipedia, there seems to be a list of them.

I think there should be an North American/ South American equivalent. I know that there is a Japanese radio clock standard that services a part of Asia. So, I gues there should be one for the Americas also.

It looks like Argentina and Brazil both transmit a clock reference signal on 10MHz with the National Observatory's DSO also on 166.53MHz and 171.13MHz.

Yeah, DCF77 is an European thing. ☺

@@DiodeGoneWild Surely the best would be a GPS PPS signal - accurate to microseconds anywhere in the world. They are in fact the basis of the majority of stratum 1 NTP servers on the internet, which I well know as I operate one!

PIC are not so fashionable, but great project anyway. I hope you are definitelly not placing that LED sh*t under the nixie tubes :D

@@teslakovalaborator PICs were my first microcontroller experience and I stuck with them. I know there are more powerful microcontrollers out there, but I come to have a pretty good understanding of PICs and their assembley language. I hate that LEDs under any type of tubes :). And even if I wanted to put LEDs under the nixies, I can't, because they are the small, solderable type and there is no place under them for any kind of led or other nonsense :).

yes, they are :) They are good for prototyping boards, as long as you don't heat them too much during soldering - the insulation would melt. They are also useful for breadboard testing.

yes, also the CAT6's ones are perfect-fit for breadboards and female pin headers

@@DiodeGoneWild For some reason my ethernet wires always end up in bad connections on the breadboard. It's weird because i believe that they have the same cross section as that of a regular hookup wire

You also can use wirerap

@@DiodeGoneWild i thouht they were from phone cables tho maybe they are the same type of wire but 4 pairs in i cable. Also are those solid or stranded? i often use solid but sometimes they break inside so i can see why stranded may work sometimes better. What type did u use or do u use what u have available?

Pen and Paper

ARM assembly and the STM32 is a lot harder than (excuse me for being contraversial) "real" RISC architectures.... if you want to get into assembly, I heartily recommend AVR chips..... they're niiice!

I used to working with stm32 and nxp mcu before I'm actually a developer and I'm now working in a company which is making power electronics pcbs for driving electromotors stm8 especially their AF series are pretty robust against industrial noises and they are also pretty cheap so now we are using them in order to making custom motor drivers for our costumers. We also working on data loggers and measurement instruments and we didn't have any problems with stm8 mcu they are cheap and they are way better than avr we test them in high electromagnetic field atmega mcus restart again and again and don't work properly but stmaf series can handle that kind of industrial noises pretty well so we use them and it's not my choice to use them i actually start mcu learning with 8051 MCUs in assembly and work with all kind of MCUs, some dsp chips and fpga chips as well and i think stm32 is easiest because st give people HALL library and stmcube do all the job for u. I should say stm8 also has spl library but u know u can't compare them it's not complete package and u still should do all the job by ur self. But i think it can be a good challenge for people who wants to get into it.

Trust me, the ULP is a pain in the ass, it's programed in assembler with a special toolchain and need some linking the .asm The ESP32 isn't very energy efficient

Maybe one day I will make a video about ASM code, but such video is going to be many many hours long... :D

ATtiny (and even some ATmega) chips can also run down to 1.8V, but in this case I use a higher voltage also because of the thermometer and the internal voltage reference for it. So I needed to be above 2.7V. But with a 2032 it would work, because it stays above 2.7V for over 90% of the discharge (its discharge curve is flat). On the other hand, alkaline battery voltage goes down very steeply as they discharge.

watches are a bit too tiny for me :). DC doesn't destroy the LCD quickly, it probably takes some time, so your display might still be good. DC can be used shortly for testing.

@@DiodeGoneWild oh okay, thanks for your answer:)

Thanks :) I used the last free pin for the temperature sensor, so no alarm. And I intended this for a living room, so I didn't need an alarm. For bedroom, I have built some LED clocks with alarm. LED ones are probably more suitable as bedroom alarm clocks anyway because you want them to be readable in the night.

Спасибо вам за ответ . Мир, Дружба , Май .

Thanks :) yes, why use more components and more cpu cycles than needed ;).

LED can working even for ages on DC (if it only not overheated). LCD can't because DC flowing thru liquid crystals causes electrolisis and this is reason why LCD need clock signals out of phases, or more precise - without having added constant dc offset. But it refers to only multiplexed signals. If you make some intelectual effort you can make it in progam by writting only one class for multiplexing and use it for drive a lot of pixels/digits witout matter about low level signals layer. Temperature is another problem but what is more interesting you is drift temperature coefficient, daily, yearly etc not it absolute value. As long as integral values of temperature differencies are constatn it not affec day to day time counter. Only temp. drifts can affect your timer. And with standard quartz 30 ppm tolerances it gave you few second for day absolute error.

@@romanowskis1at We are talking about apple and orange here. Since the temperature is not constant during days and the 32k Crystal frequency changes by temperature, so the average value of drift is not constant during the year. So you do not assume the frequency drift rate is fixed. However to measure the 32k crystal frequency accurately, you need to have a PLL and a frequency multiplexer. The LED has more hardware complexity than LCD because you need to use some external transistors and resistors. But for LCD as long as you get the voltage right you get the right contrast. For very complex LCDs, there are drivers that use i2c or spi or other protocols. You never have to do this kind of low level hardware design.

ASM is more efficient and more adventurous. I'm not going to switch the uC. If I did, I'd probably have to change the schematic too.

US seems to be self-destructed by this paranoia... Why live in constant fear and suspicion? In the 2 million year history of humankind, you hardly find a safer era to live in.

It´s a ATmega Programmable IC. You can program what you want. Some Module parts available. Retrofitting a small Radio Circuit would be the simplest Method.

@@01Hudesohn An FM/AM radio is a big story by itself. There are software control radios which can be controlled digitally and will be beyond his show and tell power supply dissectings.

the DCF77 receiver module is from ebay.

It's probably possible, but it would add a lot of extra complexity and it would be overengineered :). Indoor temperature doesn't vary that much.

Doing things the old fashioned way, taking the pain to make the clock sync is way for fun! than building things with pre-designed sophisticated modules!

Our date format is the day first, then the month, so it has to be able to display 31. 12.

Really, what is RGB + white light needed for in a clock? :D

@@DiodeGoneWild - it´s an optional nice to have to choose te color of the display you want , just like my "Rok Rugby" MP3 player from 2005

yes, why not? :)

You can't. Both are 10mV/°C, but MCP9700 output voltage is shifted 500mV up.

@@DiodeGoneWild Ok Thank you👍

Even if no longer produced, eBay is still full of them. They are probably taken from scrap electronics, but 99% of them work fine.

Low frequency crystals are roughly the same accuracy as the high frequency ones. The problem is that when using a low frequency crystal with ATmega16(A), you're stuck with the internal capacitors and you can't use external ones for fine tuning. Or at least I didn't figure out how to disable the internal ones. Maybe I'm missing something. But anyway, the digital adjustment is better than changing capacitors ;).

PL 👍👍👍

1 second per day = 11.574 ppm 1 second per week = 1.653 ppm For example, if it is 3 seconds ahead after 1 week, you need to correct it by -5ppm (-1.653 x 3)

@@DiodeGoneWild 🥺 Thanks professor you replied ❤️ this will be memorable day for me, love you from India 😇

Well only some very small pulse current flows. LCD is a capacitive, voltage controlled display, so no current and thus no current limiting. The optimal frequency for driving LCDs is 50-150Hz, that doesn't matter much. What matters the most, is the duty cycle: it has to be exactly 1:1.

Everything is relative. It’s not actually a negative voltage as far as the microcontroller is concerned, rather the 0V rail. But to the LCD this ‘looks’ negative when compared to the average voltage that each segment sees.

Drive the + pin with 5V and the - pin with 0V. You are familiar with this. The LCD will see 5V from + to - pin (5V - 0V = 5V). Now, invert this: drive the + pin with 0V and the - pin with 5V. From the + to - pin it is now -5V (0V - 5V = -5V). Alternate between the two configurations and you have generated a 10 Vpp (peak-to-peak) signal between the + and - pins. Effectively what you are doing is driving the + pin with a 0V to 5V square wave signal, and driving the - pin with the same 0V to 5V square wave shape, but shifted 180°. From the + to the - pin you would see a square wave signal of the same shape, but it would be swinging from -5V to +5V. If you do not want a square wave at the LCD, you could also change the driving signals so that the LCD would see 5V -> 0V -> -5V. (Though in reality the switching frequency and the stray capacitance of the connections are likely large enough that what the LCD sees more closely resembles a sine wave than a square wave, but I digress.) This is a nice trick you can use when you are blessed with differential signaling (i.e. you can control both the + and the - pin). This is how computer components communicate at high speed (modern RAM clocks are 1000+ MHz). The voltage is low (DDR3L was 1.35V), yet because the clock and strobe signals are differential, the swing at the driven pins is larger. (Of course there are other benefits to this, but transmission lines and HF PCB design are a topic for another time.) Hope this helps at all. Excuse the digressions :)

well, I know, I could :) but this is already complex enough. It's meant for indoor use where the temperature doesn't vary that much, so this would be what I already consider overengineered.

@@DiodeGoneWild Next project: Small thermal/atmospheric chamber so you can determine the specific effects of temperature on oscillator drift for each project :D