Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Is it possible to make a gate level digital wrist watch

Fluffyboii

Active Member
Hi,
Ever since I designed and simulated a digital watch with logic gates for one of my electronics classes in university I had this urge to take that design and make it reality with only transistors. Not even logic gates or flip flops. I did find that it is already done my different individuals and it is not an easy feat.

Anyway I am super into digital watches for the past year or so. I simply like telling the precise time at a simple glance and I love the unusual shape and sizes some digital watches have. Today the idea of making my own digital wrist watch got stuck on my mind. Obviously the easiest way to do it would be to get a microprocessor, few small 8 bit displays, rtc module for precise time keeping, slamming all of that in a 3d printed case. Even doing that would be a feat in itself.
Unfortunately using something like an Arduino, taking the Atmega something processor from it feels wrong. People make smartwatches with lots of functionality with those and just simple time keeping with it would make me sad. I could get a less powerful microprocessor and try to code in assembly to torture myself but I am not in that mood.
Using transistor level logic would never fit in a wrist watch form factor, I wonder if using smd versions of logic gate chips, flip flops, multiplexers, etc. would make it possible to fit in a wrist watch or do I need to get counter ICs and other more complex ICs for it to fit. Today most wrist watches that are digital have a small mcu, a quartz crystal with an inductor, few caps and resistors and thats it. Pretty boring and unrepairable.

I am also curious about when something stops being analog. Analog circuits are fascinating. I also want to make a calculator with all solid state components but analog in design. Adding and subtracting with op amps is easy enough but multiplication is difficult :( Obviously having it all solid state requires using some kind if led display which requires a dac at some point. Can something similar be done with a watch, nearly fully analog except the display. This is bit off topic from my initial wrist watch idea but is it possible to make a watch with a led display that does all the time keeping with an analog circuitry, just for the sake of it. Something like a RC circuit that charges a capacitor until a voltage threshold is passed that the triggers a comparator for example to keep time. I never truly understood when some circuit truly becomes digital.

This is just my random thoughts at 5am.
Edit: I just searched bit more and a microprocessor less watch requires immense amount of logic elements just as I remember that will definitely not fit in a small package unless I use ICs to do most of the hard work.
 
Last edited:
For a cheap and low power self-setting add-on, use a time signal receiver; DCF77, WWVB or whatever suits the location.

You need a single input on the MCU (or an output as well to power the receiver if you don't want it on continuously).

eg.

 
Hi,
Ever since I designed and simulated a digital watch with logic gates for one of my electronics classes in university I had this urge to take that design and make it reality with only transistors. Not even logic gates or flip flops. I did find that it is already done my different individuals and it is not an easy feat.

Anyway I am super into digital watches for the past year or so. I simply like telling the precise time at a simple glance and I love the unusual shape and sizes some digital watches have. Today the idea of making my own digital wrist watch got stuck on my mind. Obviously the easiest way to do it would be to get a microprocessor, few small 8 bit displays, rtc module for precise time keeping, slamming all of that in a 3d printed case. Even doing that would be a feat in itself.
Unfortunately using something like an Arduino, taking the Atmega something processor from it feels wrong. People make smartwatches with lots of functionality with those and just simple time keeping with it would make me sad. I could get a less powerful microprocessor and try to code in assembly to torture myself but I am not in that mood.
Using transistor level logic would never fit in a wrist watch form factor, I wonder if using smd versions of logic gate chips, flip flops, multiplexers, etc. would make it possible to fit in a wrist watch or do I need to get counter ICs and other more complex ICs for it to fit. Today most wrist watches that are digital have a small mcu, a quartz crystal with an inductor, few caps and resistors and thats it. Pretty boring and unrepairable.

I am also curious about when something stops being analog. Analog circuits are fascinating. I also want to make a calculator with all solid state components but analog in design. Adding and subtracting with op amps is easy enough but multiplication is difficult :( Obviously having it all solid state requires using some kind if led display which requires a dac at some point. Can something similar be done with a watch, nearly fully analog except the display. This is bit off topic from my initial wrist watch idea but is it possible to make a watch with a led display that does all the time keeping with an analog circuitry, just for the sake of it. Something like a RC circuit that charges a capacitor until a voltage threshold is passed that the triggers a comparator for example to keep time. I never truly understood when some circuit truly becomes digital.

This is just my random thoughts at 5am.
Edit: I just searched bit more and a microprocessor less watch requires immense amount of logic elements just as I remember that will definitely not fit in a small package unless I use ICs to do most of the hard work.
Hi F,
Analog would be a much better piece of art, with a Barney Rubble type face, or like an old car speedometer. Wouldn't moving hands by coils or similar be more fun? It would have to be a clock though.
C
 
Hi Mr a,
If GPS modules are accepted for this project, they are very accurate.
C.

Oh for sure, but I think that adds an addition layer of complexity which I never wanted. That's of course unless I wanted the GPS function for the GPS function as well as timekeeping.

In the old days we used NIST WWV :)
 
Oh for sure, but I think that adds an addition layer of complexity which I never wanted. That's of course unless I wanted the GPS function for the GPS function as well as timekeeping.

In the old days we used NIST WWV :)
Hi Mr A,
If you want accuracy and simplicity, just use the 1/second trigger for your clock, with the minimum of satellites needed.
C
 
Hi Mr A,
If you want accuracy and simplicity, just use the 1/second trigger for your clock, with the minimum of satellites needed.
C

Hi,

Yes I'm sure you do, but I don't need that I just use one of the better RTC boards. They are already assembled and all, so you just connect a few wires to your Arduino and you have some really accurate time keeping. I can live with 6 seconds per year or something like that :)

Do you have a GPS module, and if so, where did you purchase it? Maybe I'll look into it anyway. Thanks.
 
Hi,

Yes I'm sure you do, but I don't need that I just use one of the better RTC boards. They are already assembled and all, so you just connect a few wires to your Arduino and you have some really accurate time keeping. I can live with 6 seconds per year or something like that :)

Do you have a GPS module, and if so, where did you purchase it? Maybe I'll look into it anyway. Thanks.
Hi Mr A,
I have many GPS modules, up to M9Ns. I try to buy the latest, I can afford as I need a few for my project,
If you want to take a chance with these:

they will be ok for the 1/sec output, but are most likely clones, so you will need to buy the genuine modules from Ublox, and solder them onto boards like this, so you have all of the connections etc.

With these you will need at least one satellite, for the accurate clock.
An interesting thing is: if you switch yours on and I switch mine on, then they will be almost in sync. (within uS) I was going to make a project with TX and RX, to by synced with these.
Cheers, C.
 
With these you will need at least one satellite, for the accurate clock.

You need several satellites (three or more), to give a 3D fix, for the clock to be fully accurate - with only one or two, it cannot accurately measure its location & calculate the propagation delay from the satellites to the receiver.

With a good 3D lock, the PPS output from the better ublox modules is rated for an accuracy of around +/- 5nS

I have a Z9T running an RTK base station & NTP server, that's typically showing around 30 satellites with good signal strength.


You can get also boards with just a GPS receiver module that are a direct plug-in connection to such as a Raspberry Pi standard header.

The 60 or 77KHz receivers are far simpler and cheaper though, if you just want normal clock accuracy without having to bother with setting or checking them.
 
. I never truly understood when some circuit truly becomes digital.
If the signal has discrete values that represent a logic (boolean) state, it's digital.
If the signal has no discrete states, but continuous values, it's analog.
 
You need several satellites (three or more), to give a 3D fix, for the clock to be fully accurate - with only one or two, it cannot accurately measure its location & calculate the propagation delay from the satellites to the receiver.

With a good 3D lock, the PPS output from the better ublox modules is rated for an accuracy of around +/- 5nS

I have a Z9T running an RTK base station & NTP server, that's typically showing around 30 satellites with good signal strength.


You can get also boards with just a GPS receiver module that are a direct plug-in connection to such as a Raspberry Pi standard header.

The 60 or 77KHz receivers are far simpler and cheaper though, if you just want normal clock accuracy without having to bother with setting or checking them.
Hi R,
I was suggesting that by using a GPS module, there is a 1/sec output, for his watch/clock, this only needs one satellite, to fire.
C
 
This is what I made, I like it but it needs some work on the software.
IMG_2068.jpg
IMG_2088.jpg
 
I never truly understood when some circuit truly becomes digital.
All logic ICs have analog characteristics albeit non-linear since there is no gain when the output is limited but there is gain at the transition threshold. It is considered logic when it obeys the voltage level rules and has any fundamental logic functions: INV, OR, NOR, XOR, XNOR, AND, NAND. Different logic levels are rules defined for each topology and supply levels for ECL, TTL, CML, NMOS, and CMOS.

Some analog circuits, such as analog comparators with pullup R, may interface with logic.
Diode bridges act as XOR gates with the appropriate input voltages.
Also, the 4000 series CMOS with low current shoot-thru could easily be analog inverting amplifiers with negative feedback, since they had 60 dB gain.
 
Back
Top