Hello everyone,
in this thread I want to share the (long) story of the relay clock, how it came to be, the problems and what's going on today.
But first things first.
One day, I stumbled across a video made by look mum no computer titled "Retro Russian "NIXIE" VFD Clock ELEKTRONIKA 7" where he shows a russian clock and asked the question: But what does it sound like?
Well the answer was: like nothing. Silent. And that gave me an idea. Why don't I come up with a way to make a clock, which is "electronic", but sounds like it's doing something?
Since I liked electronics and a challenge, and had nothing better to do, it sounded like a good idea to keep my mind busy.
With that in mind, I started thinking about the idea. Which parts to use, how to make it, prices of everything, should the parts do the thinking oder use an IC and just let it pretend like it's doing something?
After a week or so I had my answers: relays (I like the noise they make), they should do the "thinking"(counting), they will be cheap shitty parts from china (somehow I ended up with "recycled" relays) and with actually making it - It'll work out somehow.
So I started to look for programs to design the circuit and the PCB, I ended up with Blackboard Circuit designer and a circuit simulator made by some guy named falstad I think.
It took me 4 weeks to figure everything out. I had some basic knowledge, but I have never made up something this big and this complex, all I've ever made never contained more than 5 active electronic parts.
so here is what was needed:
First off, I figured I'd make it with decimal counters. So in total, it needed 6 counting modules to get the time format HH/MM/SS, and each one has to trigger the next one once it reaches 0(zero) again.
To make this work, I somehow came up with 2 relays per digit, with a delay circuit between them. So when the first one is activated, the other one activates a bit later.
I figured out that the delay was the key thing to make everything function, everything I tried before just triggered all the relays at once.
this is what the first working circuit looked like in Blackboard:
![](https://i.imgur.com/VbHOatX.jpg)
The IC sockets are connected to work with these relays:
![](https://i.imgur.com/pM5aPNv.jpg)
So I tested this in a smaller way and it worked, kinda sort of.
Next thing: well ok, now you figured out how to make the counters, but you still need to get this to a readable format - the outputs of the counters had to be translated for a 7-segment display.
That alone took another week, and here is what I came up with:
![](https://i.imgur.com/iW1zspA.jpg)
In total around 350 diodes or something like that.
So I went onto ebay and started looking for the cheapest parts I could get.
Here is the list of components that were needed:
I think 102 Relays (came from ebay, cheapest ones were around 3€ for 10 Pcs)
102 IC sockets for the relays
about 55 NPN Transistors (again, ebay)
55 or so Capacitors (I had enough overkill 2200µF 25V ones somewhere)
55 trimpots
500 diodes
500 LEDs
555 and support components for timing
loads of wires
and PCBs (perfboard). With these I ordered the largest ones I could get for reasonable money, so I ended up with 30x18cm ones.
After everything arrived, I put it all together. Very quickly I realized that I forgot to add a reset circuit, which resets the Hours when it reached 24 hours.
also, after noticing that the LEDs I ordered are very bright, I had to somehow get the brighness down...which I somehow managed with a PNP transistor.
After many errors and mistakes, and my basic soldering skills, I managed to get it to work and this is what it looked like:
![](https://i.imgur.com/1Opm110.jpg)
it was huge. 30x18cm PCBs, and 4 boards in depth, it wasn't easy to find a place to put it. Also, I quickly made a housing for it, since it was very sensitive to movement (soldering skills.....)
after that, I noticed that with the best "tuning" it was never able to keep time properly - some googling later I found out that ne 555, resistors and capacitos shift in value with temperature
![Banging Head |O](https://www.eevblog.com/forum/Smileys/default/bangheadonwall.gif)
So I looked for a simple 1 hz generating circuit, found one with a crystal, adapted it to the existing circuitry - and there came PCB number 5 with better controls for everything.
After all, this monster of a clock worked fine for about 3 Months or so, but it had its issues.
1. even with the crystal, timekeeping became more and more of an issue.
2. Somehow, it sometimes went mad and one counter module decided to erraticly stop somewhere inbetween and messed everything up.
3. the reset circuit had a mind of its own, sometimes it simply resets the way it was supposed to or startet "flickering", and finally managing the reset after 10 or so attempts.
4. The display. Either due to my poor soldering, or due to very badly made LEDs, a lot of them failed sadly. Also, it was still very bright and able to light up a room.
5. Power consumption and distribution. In the end this thing took a lot of power- about 15 Watts at full brightness - 10 at a more humane not sun-like experience setting. but still, a lot of power, which hat to go everywhere. it came to a point where I doubled every powerline in the circuit.
6. Size. Size. Size. It was just too big. The final dimensions were 35cm wide, 23cm high, 25 cm deep.
This is the story of the first relay clock that I made, and let me tell you, there were a lot of headaches with this one.
There is video of this on youtube, if you want you can check it out here:
That's all for the first one, I have made some more to try and improve the circuit and everything else. I will show you the others too.
enjoy your day,
Daniel