
Transistor Clock - Tomte
http://www.transistorclock.com/
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theamk
This looks like a very modern design inspired by integrated circuits -- the
clock is made out of a large number of almost identical sub-circuits. This
probably makes debugging very easy, but also means that design has much more
parts than required.

One example is binary to 7 segment decode, which takes entire top of the
clock. In this clock, they first fully decode the signal to 10 wires, then
amplify it, invert it, and encode it again to 7 segments. That's a lot of
diodes, transistor and resistors!

We can look at how this was done commercially -- for example in this SN7454
datasheet from 1974, page 6 of
[http://www.ti.com/lit/ds/sdls111/sdls111.pdf](http://www.ti.com/lit/ds/sdls111/sdls111.pdf),
they go from 4-bit binary directly into segment driver. This is already fewer
parts that this clock has, and in practice, one could reduce the part count
even further, for example by grabbing both inverse and direct output of flip-
flops.

And one can get even smaller if they want to go dynamic indications. Here is a
clock with a much smaller part count: [http://lovqvist.net/DTL/old%20dtl-
clock.html](http://lovqvist.net/DTL/old%20dtl-clock.html) . Of course, that
one would be much harder to debug...

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Zenst
When you look at the cost of this ($199), you start to appreciate
microprocessors and moore's law from the cost per transistor on a chip.

~~~
ChuckMcM
First, I think this is a pretty cool site and I'm happy to see someone
creating this sort of geeky "techno-art."

As for price, it is clearly not component cost driven. Size for sure, but not
price. The "TTL" clock is only $164 (not big discount), the Surface Mount one
is $64 which is a bigger delta.

You can buy all the component parts for the transistor clock for about $20
from bulk suppliers. The most expensive part are the displays.

It would be fun to try different designs to see if you could minimize
components and improve accuracy.

[1]
[http://www.kabtronics.com/orderpage/index.html](http://www.kabtronics.com/orderpage/index.html)

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jeffwass
Obligatory mention of “The Clock”, a veritable piece of artwork soldered from
hundreds of individual diodes and transistors. The bare uninsulated component
wires form part of the artwork.

[https://techno-logic-art.com/clock.htm](https://techno-logic-
art.com/clock.htm)

Picture inside it’s own frame : [https://techno-logic-
art.com/images4/fc1.jpg](https://techno-logic-art.com/images4/fc1.jpg)

~~~
ChuckMcM
Ok, that is super cool.

~~~
squarefoot
Although unpractical in many ways, and coolness factor aside, that building
style made sense in the old days when power supplies didn't break and
capacitors didn't leak, so there was very little chance of having to change a
faulty part even after years of use. I still have some NOS capacitors from the
70s whose manufacturer is gone since ages, and they still exhibit higher
capacitance than advertised and lower ESR than any new cheap Chinese
counterparts which sometimes die within one year of use or less.

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Osiris
My brother-in-law has this in his kitchen. It's huge and, apparently, takes a
very long time to assemble / solder.

