EEVblog #801 - How To Design A Digital Clock

[Howardlong]

I assume the same problem exists for renewable feed-ins, albeit at a much lower power. How do they synchronise for maximum power transfer?

[LabSpokane]

Interestingly enough, one of the things we got to do in the EE power lab was to synch generators up to the grid.  It's actually possible to do with three light bulbs, one for each phase.  When there is a difference in phase between your generator and the grid, the bulbs will illuminate proportionally to the phase difference.  As you bring your generator into sync, the bulbs go dark, and then you can transfer your generator onto the grid. 

Crude, to be sure, but it was a great visual introduction into phase synchronization. 

[LabSpokane]

I assume the same problem exists for renewable feed-ins, albeit at a much lower power. How do they synchronise for maximum power transfer?

I'll ask.  I know that it's a problem because the renewable generators like to push in 100% of the generation regardless of the demand.  This forces the utilities to not only follow the load, but also follow the renewables generation level. The phase synchronization technique varies with wind turbines since some are synchronous generators and some are induction, so the latter has slip. 

[jancumps]

...Perhaps you should check people's profiles once and a while.
...

I did, and the first hit was "Why has AG6K been Banned Here ?" Must use a different search mechanism...

[AF6LJ]

...Perhaps you should check people's profiles once and a while.
...

I did, and the first hit was "Why has AG6K been Banned Here ?" Must use a different search mechanism...

You obviously didn't click on my screen name over to the left did you?

[jancumps]

I didn't at first . I did now.

[AF6LJ]

I didn't at first . I did now.

Even in this day and age finding a female in this business is uncommon.
Think of what it was like when I started in the mid 70s.
If it wasn't for one acquaintance of my family that owned a service shop in Oregon I would likely not had made into electronics as a career let alone RF and two way radio.

[ez24]

Interestingly enough, one of the things we got to do in the EE power lab was to synch generators up to the grid.  It's actually possible to do with three light bulbs, one for each phase.  When there is a difference in phase between your generator and the grid, the bulbs will illuminate proportionally to the phase difference.  As you bring your generator into sync, the bulbs go dark, and then you can transfer your generator onto the grid. 

Crude, to be sure, but it was a great visual introduction into phase synchronization.

Do you know of any videos on this?

[LabSpokane]

Interestingly enough, one of the things we got to do in the EE power lab was to synch generators up to the grid.  It's actually possible to do with three light bulbs, one for each phase.  When there is a difference in phase between your generator and the grid, the bulbs will illuminate proportionally to the phase difference.  As you bring your generator into sync, the bulbs go dark, and then you can transfer your generator onto the grid. 

Crude, to be sure, but it was a great visual introduction into phase synchronization.

Do you know of any videos on this?

No.  Sorry.

[warp_foo]

I still keep candles, and have very occasionally used them.

Same here. They get used every time there's a power cut. A couple of christmases ago we had no power for about a week. In the end they parked a big mobile genny in the street to give everyone power on christmas eve. I was actually a bit disappointed; I was looking forward to a BBQ in the cold/rain.

The frequency of power cuts was also a large part of my reasoning behind getting a butane soldering iron many years ago. The idea being it would give me something to do in a power cut. There's been lots of power cuts since and I don't think I've ever used the butane iron during one, so that turned out well. Nowadays I mostly use it to shrink heatshrink.

Blimey, where do you live? The only time we had a power cut since the glory days of trade unions in the 70's was a year ago when I noticed my server powering down and rebooting and then the house lights dimming randomly. I chucked one of those power meters into a socket and found the mains had dropped as much as USA levels but hovered around 160VAC. Out on the street all the sodium lamps were flickering or off. Turns out on the high street the underground transformer caught fire and there were flames coming up from the paving stones. Quite bizzarre experience.

As for butane iron. I got one thinking it would be good for fixing stuff on the car... erm... maybe not 

In Minnesota we are very prepared for whatever may come in during the winter. North Carolina, not so much.

In general, an NC winter is usually a bit frigid, somewhat damp, and usually overcast. Every few years, however, NC gets some fairly severe ice storms. The last one I was there for - maybe '96 or '97 - we were out of power for 3 full days. Pretty much every major power company East of the Mississippi sent crews to assist in getting the power back online. (Pro Tip: Kerosene heaters are not capable of warming up much more than a mid sized bedroom.)

If it isn't an ice storm and NC gets any snow coverage, you'll see news reports of the stores getting cleared out of food and bottled water. Really...

m

[apis]

I have seen universal clock chips before while browsing data sheets.
I think it is silly for you to just catigorically say I am wrong.

 
Again, I'm not the one making claims!
You made a claim (well, you backed up someone else's claim, saying it's "factual") that the clock counted down. You get to prove it, that's how it works.
I'm not saying it's not possible, but it seems unlikely. It's a reasonable position to hold until you actually provide evidence or proof.

You said, and I quote:

Good Job, all factual.

in response to these supposed facts:

2.  The clock was altered into a countdown timer, rather than an RTC.
3.  Said clock/timer was executing an active countdown when the incident occurred.

Prove it.

I am simply backing up what was reported in the news. You are making the claim I am somehow wrong without anything to back it up.
But hay..
I get it.

Really... do you have any links to the news reports saying he had modified the clock to be a countdown timer? (And no, the hate-sites doesn't count as "news", real news sites like wall street journal or new york times, etc.) He either smashed a clock with a rock and threw the remains into a pencil case or he shrewdly modified the clock to be  countdown timer, you can't have it both ways. And in the end it doesn't matter, because it was stupid of the teachers to call the cops either way. You complain you live in a police state, yet you applaud when teachers call the police when a kid brings a clock mod to school and show his science teacher.

[apis]

It depends heavily on how the grid is managed.

Here in Europe, a frequency is guaranteed at normal times, there is very little variation, due to phase sync of a big number of grids.
The reason is that there is still a lot of domestic appliances keeping time based on the grid.
Advantage is the drift is limited to, say, 30s. With a quartz based clock, the drift is not limited, and you have to trim the clock time every few months.

Do you know how they do it in fennoscandia, I know there is a HVDC connection from southern Sweden to Germany. I think there is a link via the bridge to Copenhagen as well, Not sure if that is AC or DC though. I have a vague memory of reading the mains frequency is kept synchronized here as well but it was some time ago.

[cezar]

You guys have too many semiconductors in your clocks
http://thestuffwebuild.com/2015/07/the-electromechanical-relay-clock-project-is-complete/

Sent from my LG-D802 using Tapatalk

[apis]

Love the clicking of the relays, but wouldn't wan't it in my bedroom.

[Delta]

If you throw a three phase alternator onto a bus, it will either trip its breakers or lock to the bus frequency.  How close to synchronization it is when you throw the switch determines what happens. Like a previous poster said, lamps can be used, but there was always a syncrometer for the tech to use. I'll try to find a video, probably someone doing it on a ship...

AC generators on a common bus are phase locked by definition.  The amount of power they contribute (or consume! that's why there are always reverse power trips) depends purely on the torque provide by the prime mover.

[Macbeth]

I was just idly thinking what a waste of energy bench electronic loads are, chucking it away as heat, surely it could just be fed back into the mains? Not necessarily back into the grid (especially considering the pathetic amount paid for it these days), but just to take the burden from all the other lab gear, washing machine, microwave, lights, etc. on the mains from the electricity company and your bill.

Extra advantage - no need to dissipate all that heat. Run your load cool.

I found what look like some expensive commercial versions of this. Any DIY?

[EEVblog]

You guys have too many semiconductors in your clocks
http://thestuffwebuild.com/2015/07/the-electromechanical-relay-clock-project-is-complete/

That would drive the wife nuts! 

[Tac Eht Xilef]

You guys have too many semiconductors in your clocks
http://thestuffwebuild.com/2015/07/the-electromechanical-relay-clock-project-is-complete/

I need to find the pics of the uniselector & RP / one-plane readout clock I built during a few lunchtimes 30-odd years ago.

Now, where did I put those old Polaroids...?

[AF6LJ]

You guys have too many semiconductors in your clocks
http://thestuffwebuild.com/2015/07/the-electromechanical-relay-clock-project-is-complete/

Sent from my LG-D802 using Tapatalk

I like that soothing, I could go to sleep listening to that.

[AF6LJ]

I have seen universal clock chips before while browsing data sheets.
I think it is silly for you to just catigorically say I am wrong.

 
Again, I'm not the one making claims!
You made a claim (well, you backed up someone else's claim, saying it's "factual") that the clock counted down. You get to prove it, that's how it works.
I'm not saying it's not possible, but it seems unlikely. It's a reasonable position to hold until you actually provide evidence or proof.

You said, and I quote:

Good Job, all factual.

in response to these supposed facts:

2.  The clock was altered into a countdown timer, rather than an RTC.
3.  Said clock/timer was executing an active countdown when the incident occurred.

Prove it.

I am simply backing up what was reported in the news. You are making the claim I am somehow wrong without anything to back it up.
But hay..
I get it.

Really... do you have any links to the news reports saying he had modified the clock to be a countdown timer? (And no, the hate-sites doesn't count as "news", real news sites like wall street journal or new york times, etc.) He either smashed a clock with a rock and threw the remains into a pencil case or he shrewdly modified the clock to be  countdown timer, you can't have it both ways. And in the end it doesn't matter, because it was stupid of the teachers to call the cops either way. You complain you live in a police state, yet you applaud when teachers call the police when a kid brings a clock mod to school and show his science teacher.

To be honest any information I post here you would consider hate, as is usual often the truth is seen as hate speech by some.
Good Day.

[apis]

To be honest any information I post here you would consider hate, as is usual often the truth is seen as hate speech by some.
Good Day.

It doesn't matter what I consider hate speech, you said it was reported in the news and a fact.

The truth isn't hate speech (at least not if it's the truth the whole truth and nothing but the truth), but if people make up lies and spread rumors that are not true in order to discredit someone because they have a certain religion that is hate-speech in my book.

[adprom]

Dude, whether it is possible or not is irrelevant. Conspiracies are being stated as fact. On one had, the conspiracy nutters are saying well he didn't design anything and just disassembled a clock and reassembled in another receptacle to discredit him technically.

First off I am not a DUDE, I am female. Perhaps you should check people's profiles once and a while.
And no I am not going to address your comment, not worth the bandwidth here.

Firstly, in Australia dude is regularly used as a general reference without implying gender. No need to get your knickers in a knot.

What you have stated so far is no more than an unproven conspiracy.

And you have evidence the clock was only disassembled? please lets see it.

You don't seem to understand how this works. You are making claims without evidence, the impetus is on you to prove it - not for others to prove the negative assertion. This is basic stuff (something which conspiracy theorists and 'truthers' tend not make a mistake with.

When you have provable facts please come back with them and their sources.

I'm not the one making a claim - it is up to you when saying something is true to back it up. I am simply questioning the claims - it is not up to me to provide evidence that it isn't true. That isn't how it works.

So that's the point, if you make a claim, it is up to you to prove them with evidence. Not for me to provide evidence otherwise.

[bartm]

Hi Dave,

fun stuff to watch as usual. Just wondering about the carry from the seconds to the minute, and the minutes to the hour.
Shouldn't it be the reset there in stead of the carry ? the carry will only pulse on a 9->0 transition i presume.
See my scrible on the schematic.

regards,
Bart

[Macbeth]

Hi Dave,

fun stuff to watch as usual. Just wondering about the carry from the seconds to the minute, and the minutes to the hour.
Shouldn't it be the reset there in stead of the carry ? the carry will only pulse on a 9->0 transition i presume.
See my scrible on the schematic.

regards,
Bart

Well spotted, that makes sense to me. Now enough of that, can we get back to all the bomb talk  and conspiracy theories please? 

[EEVblog]

fun stuff to watch as usual. Just wondering about the carry from the seconds to the minute, and the minutes to the hour.
Shouldn't it be the reset there in stead of the carry ? the carry will only pulse on a 9->0 transition i presume.

No, the carry goes low once it hits 5 (see timing diagram) so the reset then switches it back high. So it works for any count >=5
http://www.ti.com/lit/ds/symlink/cd4026b.pdf