The (long) story of the relay clock

[Spemo]

What program did you do the schematic in?

I made this in Blackboard Circuit Designer.  It has all the parts needed for this project.

http://synthbu.de/blackboard/

I don't know how to set the language though. I've read on a forum somewhere that it can be set to english, or it does it by itself

You're crazy, but it's a nice kind of crazy that happens to engineers when they get an itch that needs scratching. One question though, where did you get those large sheets of perfboard?

I got them off Ebay, there is one seller who sells them at a reasonable price, around 15€ for 5 of them. They come straight from China, sadly they are a little bent, but properly mounted it works ok.
 Just search for 18x30cm PCB and set it to world wide search.

[edavid]

As promised, here is the "Schematic" I use to build this monster - maybe one of you can find some use with this.

That is a "pictorial diagram" rather than a schematic.  Is it possible to create a schematic?

[TomS_]

Welcome to the crazy clock club.

Here's mine: ornotblog.blogspot.com

😁

[Spemo]

As promised, here is the "Schematic" I use to build this monster - maybe one of you can find some use with this.

That is a "pictorial diagram" rather than a schematic.  Is it possible to create a schematic?

something like this?

[rstofer]

That's some nice work.  You clearly have more patience than I.

[edavid]

As promised, here is the "Schematic" I use to build this monster - maybe one of you can find some use with this.

That is a "pictorial diagram" rather than a schematic.  Is it possible to create a schematic?

something like this?

(Attachment Link)

Yes, exactly, although it turned out to be only slightly more comprehensible than the pictorials 
Thanks...

[Spemo]

Yes, exactly, although it turned out to be only slightly more comprehensible than the pictorials 
Thanks...

Well here you go, I drew something up in tinyCad with the right values. I did this quickly, so this is only the 3 digit version with startup circuit.

[edavid]

Thanks, much easier to understand!

[maxwell3e10]

Now a really crazy idea would be to make a "digital" clock without any semiconductors. Use a mechanical pendulum for timing, relays for counting, and small incandescent lightbulbs. I wonder if such a thing was ever made during the early electric era.

I find it curious that most popular wrist watches use the opposite approach now, a quartz oscillator but mechanical hands. They have never appealed to me.

[texaspyro]

Now a really crazy idea would be to make a "digital" clock without any semiconductors.

I've seen a digital clock where all the counting, display, etc was done with neon lamps. 

[maxwell3e10]

Yes, I guess I've come across these projects too, using a Dekatron or just individual neon tubes as gates. But that is very advanced 20th century technology:) Using relays, incandescent lamps and a pendulum one can stay entirely in the 19th century.

[Spemo]

Now a really crazy idea would be to make a "digital" clock without any semiconductors.

It is possible, I have a "pictorial diagram" for this, but it would double the amount of relays. Capacitors are a must though.
Then you can definately say it's a rats nest of wires.

Oh, and accuracy would be hard to get aswell

[texaspyro]

Now a really crazy idea would be to make a "digital" clock without any semiconductors.

It is possible, I have a "pictorial diagram" for this, but it would double the amount of relays. Capacitors are a must though.
Then you can definately say it's a rats nest of wires

No relays or transistors were in the neon clock...

[Spemo]

No relays or transistors were in the neon clock...

Ok, but I think that would require high voltage, and I don't want to go there honestly....

Now a really crazy idea would be to make a "digital" clock without any semiconductors. Use a mechanical pendulum for timing, relays for counting, and small incandescent lightbulbs. I wonder if such a thing was ever made during the early electric era.

This is what I meant would be possible

[maxwell3e10]

Here is one approach using just relays and resistors to build a counter.
https://www.ee.ryerson.ca/~phiscock/papers/relay-counter.pdf

[macboy]

The high power consumption and the fading/failing LEDs is caused by not having current limiting resistors on the LEDs. You are directly driving them from the power supply, which is a bad idea.  LEDs designed to be driven directly by 5 V or 12 V are avaialble (with built in current limiting resistors) but I don't think that's what you are using.

[Spemo]

The high power consumption and the fading/failing LEDs is caused by not having current limiting resistors on the LEDs. You are directly driving them from the power supply, which is a bad idea.  LEDs designed to be driven directly by 5 V or 12 V are avaialble (with built in current limiting resistors) but I don't think that's what you are using.

they all have current limiting resistors - the values of the resistors are calculated to run them at around 10-15mA per LED(don't remember exactly). They can handle 20mA without a problem, but I don't want to run them that hard.

[Spemo]

Hey everyone....

Since I still have to wait atleast a week to get all the parts for CV8, I decided to build another CV7....I don't know why, but I guess I don't have anything else to do....

This time I'd like to show you step by step, and also keep track of the time spent building this thing, since I have no idea how long it really takes.

So lets start.

The first thing that had to be done was to modify standard 16pin IC-Sockets by removing not needed connections.

I decided to put all the relays back into sockets, since the relays do fail some day, and also, because I went the cheap way, I ordered the cheapest and got relays that have been desoldered somewhere.
They are chinese relays either way (new or not, named HK19-F), I have no idea how old they are and how many cycles they went through. Desoldering them when they fail is a huge pain and also ruins the copper pads on the perfboard. So sockets it is, not as stable, but easy to service.

So, they had to be soldered onto the Perfboard:




Modifying, soldering and aligning them to sit straight took about 3 hours.

Then, the transistors for the counter modules had to be soldered in:



The resistors and capacitors followed:

 

The not so nice soldering ( I have shaky hands, so this is as good as it gets):




and at last for today, all the flyback diodes:




Total time spent building this so far: 6 Hours.


Now, I'm not rushing this build, in my experience, doing this quickly ends up in a lot of errors and mistakes. So we'll see how long this takes.

If you have any questions, fell free to ask them.

Have a nice day

Daniel

[schmitt trigger]

Now, I'm not rushing this build, in my experience, doing this quickly ends up in a lot of errors and mistakes. So we'll see how long this takes.

Daniel

Sage words. Rushing any project, specially a complex one like this, is a certain recipe for disaster.

Emphasis is mine.

[Spemo]

Hello again,
today I carried on with the build of CV7#2.

first, the power and ground lines were soldered in.
Then, the output posts were put in.
after that, the connections from the transistors to the relays were made, then the connections from the top row of the relays to the bottom.

The next step is already prepared, I had to cut 44 short wires. They will mostly complete the counting modules, but you'll see.

       

Time spent for the progress today : 3 hours

Total time spent building this: 9 hours


havea nice day


Daniel

[Spemo]

Hello again!

A few days ago the last missing parts for CV8 finally arrived. So I decided to stop working on CV7 #2 and start CV8.

all the counter modules on CV7#2 are done and tested, they work fine.

One day I'll finish it, or maybe inbetween, I don't know yet. When it's done, I'll see what to do with it, since I have to order a complete set of relays for it, and proper (ebay) ones that have unmodified leads are around 50 - 60€ for the 110 or so needed, Maybe I'll keep it as a spare, or maybe someone wants it when it's finished. Who knows.

So I've started with CV8.

The background story:

Since the CV7 is still kind of big, and is more something you hang on a wall like a picture, I wanted to find a way to make it more compact. Now I knew I couldn't keep the depth the same, but atleast it could sit on a shelf, as long as there is an outlet nearby.

Also, the idea of making an alarm clock out of it was wandering around in my mind. I know how I'd have to do it from the electric side of things, but I don't know how to fit it into the very limited space I allow the clock to have. So we'll see.

Long bla bla short: more compact, but basicly same circuit.

But some changes had to be made.

The first thing I came up with was something I have used with the first version - multiple boards. In the PCB "design" program I managed to fit everything onto 3 PCS including the display.
The PCBs are the cheapo ones from ebay 10x22cm.

Here is the layout:



To make everything fit and to keep the displayboard clean, I had to do some changes and some stuff had to go.
First thing that I decided to do was to put all the capacitors on the backside of the PCBs.
Then, the display had to sacrifice some stuff. It will not have 7 segment displays for the seconds, it will have some simple LEDs connected directly to the outputs of the counter modules. This saves a lot of wires, diodes and space on the PCBs.

The rest will be pretty much the same.

So I've been working on this for the evenings now, total time spent is 14 hours so far.

I guess this version is as small as it will go, the only thing I could change would be the capacitors, so they can fit between the relays. But for that I have to go lower in capacity and higher with resistance, and I haven't had the time, motivation or all parts to test it out.

Here's my progress:

     


Have a nice day


Daniel

[Spemo]

Hello everyone,
a little update.

Today I was able to finish the first of the three PCBs and test it. Thankfully, and for the first time ever, everything worked right away.
Looks like I finally found the right way to wire this up.

Doing all of this in this compact way does come with drawbacks though. Everything takes twice as long, and the limited space makes it very hard to fit and route everything, without it getting out of control.
This "rats nest" turned out to be the most challeging so far, since I have to consider every direction of the wires twice.

Also, I started the second PCB.
as always, some Pictures of the progress:

     


Time spent today: 4 hours

Total time: 18 hours.



Have a nice day

Daniel

[Spemo]

Hello again, another little update.

Some progress has been made, and a few mistakes aswell. Also, I realized there are some problems.
So here we go!

I finished up the second board, but I could't figure out how to wire up the signal converter diodes without everything getting super thick.
So I went the easy (or lazy...) way and decided to put that on another board, but then make it as flat as possible. Board 2 now has the DC-DC converter on it.

So it will have 4 boards in the end.
Here are some pictures:

     

But I got tired of soldering for now, and, as someone mentioned, a proper PCB would be better. So I forced myself to learn something new (expressPCB plus) to design a proper PCB. Then I found JLCPCB, noticed that I can't upload the files of that program since it doesn't export any gerber files. so I had to learn to use KiCAD. I hope I figured it out, I will order some test PCBs soon.

The worst thing of all this is that I have to "translate" my complete "pictorial diagram" into KiCAD. I've been working on that for 6 hours, the counter modules are in and the display, but nothing else.
Also, which is new to me, I will use a 2 layer board.
The size of it is already known, but it's a large board (282x356mm) and for 5 PCBs JLCPCB charges 55€ + 17€ shipping. So it is quite expensive, but I guess if I calculate all the wires and solder and everything else, it doesn't look as bad.

Maybe more layers can fix it, but since I can't change the size of the relays it won't go under 200x300. and the price at 4 layers is still the same, but makes it much more complicated.

so the price for one complete build would be:
15€ per PCB
30€ for 110 used/recycled china relays
3€ for 100 capacitors
3€ for the diodes
3€ for resistors
4€ for 200 NPN , and 50 PNP transistors
around 7€ for the timing circuit
1€ for 10 NE555
and depending on what you want 5€ for the display LEDs.

Total cost: 71€.

That all depends on what the current pricing on ebay is and how much you already have.


Have a nice day,

Daniel

[Spemo]

Hello again,

as promised, a small video where you can hear what the relay clock sounds like.

Every version sounds similar to this one.



Also, since I really got fed up with hand wireing this thing, I ditched the signal converter and decided to make a simple display directly from the outputs of the counter modules. I'll put some caps over the LEDs with numbers on it to see what time it is.

This version also showed the limitation of hand wireing and perfboard, and I've decided that this will be the last hand wired relay clock I'll make (at least for a while).

I learned to use KiCad and discovered JLCPCB, so a proper PCB is coming for this.

I have two designs, one single board and one multiboard solution, almost completed.

But, as everything has a colst, both options are expensive for me. The single board would cost me around 65€ for 5 PCBs, the multiboard around 50€ for 5 sets of 3 PCBs.

If I wanted to build 5 complete clocks (multiboard) I'd be at 231€ with "recycled" relays. A lot of money which I can't spend right now, but I will eventually.


Have a nice day

Daniel

[Spemo]

Hello again!

After almost 4 months of nothing, I finally managed to throw some money at this project and get some PCBs ordered and assembled.

This is CV15, which will hopefully be the last version for now.

Of course, the PCBs didn't come without some mistakes, but nothing too serious and I was able to fix everything.
But from the beginning.

In a local shop, I found some nice wooden boxes and decided to make the PCBs fit in them, with the relays that I already had.
Unfortunately, the shop stopped selling them, shortly after I placed my PCB order - bummer.
Oh well. then I tested all the relays I had, since I baught them used, I thought that would be a good idea. of all 220 I had, about 15 had weak coils.
So in the last minute, I decided to order IC sockets to put those relays in there, since they will fail eventually. This also meant, that the whole assembly wouldn't fit in the small wooden box anymore, so I now have to make my own one.

While assembling and testing, I found out that I forgot some traces in the design process, which called for some bodge wires, nothing wild.
Also, the inputs of the display PCBs were in the wrong order. Took me almost an hour to figure that out.

Also, some of the solder pads were too close together for my liking.

Other than that, within the first 30 minutes of it finally running, another relay went weak and had to be replaced, at this moment I was very thankful for the (quite expensive) sockets I put in.

Conclusion:
- total cost of ~100€ including shipping and import taxes for 5 sets of PCBs and some parts, without relays.
-some issues, but fixable. the next PCB order would be without those problems.
-It's time to finally admit to buying new relays, not used ones. sure, they are at 0,20€ each, but the failure rate is quite high.
- I have to find another housing for it, or make my own one.

Other than that, time will tell how well it goes.

This is as compact as it gets with these relays.

As always, here are some Pictures.






Have a nice day

Daniel