College Project... clock I designed in 1977-78

F

Frank4d

Gawd
Joined
Oct 29, 2005
Messages
715
I designed and built this clock for my second year electronics lab project and I earned an AS in Electronics Technology in 1978. It has 14 ICs plus 6 LED displays and is still keeping time 27 years later in my garage. But my wife won't let me bring it inside the house. :(

DCP_3994.jpg

DCP_3995.jpg

DCP_3996.jpg
 
I've got some crazy respect for the old-school engineering in that.
I like it!
-Ghent
 
That's awesume man.. I always enjoy the amount of circuitry that it took to do something like that back then :)
 
LEET
oh man, that thing looks aweseome
how did you time it?
 
Yeah... 27 years ago it took all that to make a digital clock. I still have a notebook with the schematic somewhere. It takes the 60Hz from the power source and divides it by 60, a bunch of counter chips to display hh:mm:ss, a few more chips to reset the minutes and seconds counters to 00 when they count up to 59... and hours to 1 after 12, a couple of chips to interface the toggle switches... and seven segment LED display drivers.
 
The AC outlet 60hz doesnt change? I thought it was like the voltage and would fluxuate a little.
Oh yes, that is certianly a nice clock. Really, its neat :)
 
awdark said:
The AC outlet 60hz doesnt change? I thought it was like the voltage and would fluxuate a little.
Oh yes, that is certianly a nice clock. Really, its neat :)
Click to expand...

The electric company usually keeps it at exactly 60 Hz. And if they don't (like it goes up to 60.5 Hz for a while) they will actually adjust it back to 59.5 Hz for a while to compensate... so as not to piss off people who have clocks running from it.
 
awdark said:
The AC outlet 60hz doesnt change? I thought it was like the voltage and would fluxuate a little.
Oh yes, that is certianly a nice clock. Really, its neat :)
Click to expand...


No, the frequency of the power grid is controlled pretty carefully, given the consequences of ignoring it... If you ever get a chance, take a class on power generation & distribution. Even if you don't take away any useful knowledge from it, you'll end up having a healthy respect for the folks that pipe the juice into your house for a few cents per KWh.

By the way, awesome clock there- much better engineered and built than the $10 quanta of bovine excrement that grace the shelves of modern retailers...
 
awdark said:
The AC outlet 60hz doesnt change? I thought it was like the voltage and would fluxuate a little.
Oh yes, that is certianly a nice clock. Really, its neat :)
Click to expand...
As everyone else has said here, they keep it pretty accurate. Do most modern clocks still use it as part of the timekeeping?
 
Rombus said:
As everyone else has said here, they keep it pretty accurate. Do most modern clocks still use it as part of the timekeeping?
Click to expand...

I believe they rely on the accuracy of internal oscillators now.
 
Adisharr said:
I believe they rely on the accuracy of internal oscillators now.
Click to expand...

As far as I know, mass produced digital clocks have always relied on quartz crystal oscillators. While using the frequency of the power from the outlet is a very smart idea and accomplished the job well without using a crystal and some more complicated circuitry, quartz does a better job, and allows the same theories to run all kinds of clocks and watches.

Oh, and props to the OP ;) Very cool
 
Most of the wall clocks you see in businesses & school are actually still reliant on the 60Hz of the power mains. That way, they will always be in sync, regardless of power dips/spikes, higher frequency/lower frequency, etc.

 
very cool, nice work. is it adjustable for daylight savings time? either way, nice little project.
 
santaliqueur said:
very cool, nice work. is it adjustable for daylight savings time? either way, nice little project.
Click to expand...
I assume he can set the time on it, so it should work with daylight savings time.
 
yeah, nowadays you can do all that with a handful of transistors and a 2 dollar microcontroller. :D

protoboard1.jpg

protoboard2.jpg


Frank4d said:
Yeah... 27 years ago it took all that to make a digital clock. I still have a notebook with the schematic somewhere. It takes the 60Hz from the power source and divides it by 60, a bunch of counter chips to display hh:mm:ss, a few more chips to reset the minutes and seconds counters to 00 when they count up to 59... and hours to 1 after 12, a couple of chips to interface the toggle switches... and seven segment LED display drivers.
Click to expand...
 
meh, so, now we ask, how do the power companies manage to keep "perfect" time
 
santaliqueur said:
very cool, nice work. is it adjustable for daylight savings time? either way, nice little project.
Click to expand...

It is adustable for daylight savings time. I toggle the hours adjust switch in April and toggle it again in October. I could have automated all that... but it would have required the clock to know the current month, day, and time zone.... which would have required more chips, some firmware, and would cost several $1000s in 1978.
 
if you dress it up a little bit (a case mode perhaps?)....maybe then your wife will let you take it in the house....could even use it as a nightstand clock.
 
by carefully monitoring the RPM of the generator turbines and by accordingly regulating the steam pressure, it's really not that difficult when you think about it.

killa62 said:
meh, so, now we ask, how do the power companies manage to keep "perfect" time
Click to expand...
 
corran_horn314 said:
lmao, someone should make a large old school(nixie tube maybe) display like that :D
Click to expand...
They used to have them for the stock exchange and such.

OP: Nice job on the clock. I also like that old school logic stuff, here's one I made from a decade board out of an early 70's scrapped freq counter:

front.jpeg

back.jpeg

top.jpeg

meter.jpeg

Hard to see in these pics, but I removed the movement from a d'Arsonval meter and wired it to the seconds pulse creating a pendulum effect. Pretty cool because when the movement pegs out it makes an audible click in sync with the changing seconds display.
 
killa62 said:
meh, so, now we ask, how do the power companies manage to keep "perfect" time
Click to expand...
They derive time from a GPS [font=Arial, Helvetica, sans-serif]Satellite Synchronized Clock[/font]... in most cases that signal comes out in some form of IRIG, and the devices they use implement the IRIG time signal.


Here is an example of one:
http://www.selinc.com/sel-2407.htm
 
After everyone talking about how that's so much simpler these days...

I couldn't do that with today's stuff
biggrin.gif


This is going on my list of "Things I wish I knew"
 
you'd be surprised how simple that "assface" LED display i posted is. Given, it was kinda tricky to wire up on the protoboard, but thats simply because you need to put a lot of wires into a small space.

DudeItsMe said:
After everyone talking about how that's so much simpler these days...

I couldn't do that with today's stuff
biggrin.gif


This is going on my list of "Things I wish I knew"
Click to expand...
 
awdark said:
The AC outlet 60hz doesnt change? I thought it was like the voltage and would fluxuate a little.
Click to expand...
It can't fluctuate. If it did, it would put the AC power out of phase with sources that were not fluctuating -- and that would be very bad for the grid.
frank4d said:
But my wife won't let me bring it inside the house.
Click to expand...
What's wrong with her?
 
You must log in or register to reply here.
Back
Top