Analogue clock circuits?

Were analogue circuits ever used in Digital clocks ? (aka. transistors instead of IC's). As far back as I can remember, even in the 80's, Elementary Electronics magazine used a huge, many-pinned dedicated clock chip for a clock project. Is this possible, or would it require literally hundreds of transistors?. As a sidenote, my roommate in College in 79, had a "Digital Clock" that used a complicated arrangement of motors, cams, and microswitches to illuminate light bulbs in 7 segment displays. It was incredibly complicated, and well thought out, but was probably one of the few "Digital" clocks that hummed and clicked while it ran.

Kim

"A Man Of True Frankensteinian Proportions"

Reply to
K `Sleep
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Talking electronics did a digital clock in the 80's that used a bunch of counter IC's and some transistor logic. keeps 100% perfect time to this day (gets it's clock off the mains 50 Hz).

This is about the minimum practical integration level for a hobbyist project, without blowing out the cost to a crazy figure.

Reply to
Craig Hart

Sounds like a nixie tube clock - had one myself quite some time back, and a friend had a frequency counter with them. Watching the nixies flash all over the place keeping up with an input waveform was fun. :-) There's too many transistors involved to make that a viable method (doable, but why?) - clock IC's were about the first to come out once dedicated IC's became common in the late 70's.

Cheers.

Ken

Reply to
Ken Taylor

No. Regardless of whether the circuit uses discrete transistor or IC's, it still operates in a "digital" way. Transistors can be used (and are in IC's) to form "digital" devices.

Digital counter IC's have been around as long as the display technology to build digital clocks, so they have always used IC's.

Yes it is possible, and yes it would require many hundreds of transistors. It would be a silly thing to do.

Dave :)

Reply to
David L. Jones

The display technology pre-dated ICs. According to

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- first mass-produced display tubes - late 1930s

- Nixie tubes - 1954

I built a Nixie clock in aboult 1973, but that did, of course, use ICs (TTL).

It seems people still build the likes of Nixie clocks - e.g. see

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Andy Wood snipped-for-privacy@trap.ozemail.com.au

Reply to
Andy Wood

"Andy Wood" :

** I remember there being a digital clock kit building *craze* in Australia from about mid 1973 onwards.

The early kits used a bunch of TTL and high voltage TO92 transistors to drive nixie tubes - then a dedicated clock IC appeared that meant only one IC was needed and also a dedicated fluorescent clock display appeared by about 1974/5.

Also in early 1973, the first 3.5 digit Digital Multimeter kit design appeared in Electronics Australia - it used a set of special Fairchild LSI ICs ( white ceramic with gold pins ! ) and 7 segment LED displays. It was a mains powered unit fitted into a "hammertone" metal box.

I assembled one for "Edge Electrics" back then.

........ Phil

Reply to
Phil Allison

Yes, Nixie Tubes and other types of displays (e.g. the electro-mechanical "flipper" type) have been around a long time, but as far as I am aware the consumer digital clock craze did not take off until the advent of IC's to do the job in the early 70's.

Dave :)

Reply to
David L. Jones

Our first 'digital' clock was a motor-driven beast which flipped the numbers over one by one. Hummed along quite nicely, not a transistor in sight. Well, except in the radio portion, and that died first. :-)

Cheers.

Ken

Reply to
Ken Taylor

I guess this is where the definition of "digital" starts to get a bit tricky!

Dave :)

Reply to
David L. Jones

Where about are you? My 50Hz strays out and doesn't end up exactally. Over time my 50Hz clocks end up almost 7 seconds per day off atomic clock via internet.

Reply to
Dand

A flow of water ticking over a bamboo wheel with 2 spokes? Digital enough for ya? Then maybe the first digital clock was 1400 years old.

But as this is electronics group then the motor and bamboo don't count!

Reply to
Dand

Awesome.

I built a clock out of nand gates (I scored a pack of 400 quad nand gates). What a mess it was. I think it ended up being about 60cm long on 4 way bread boards. I needed about 100 capacitors to smooth the power on all the ICs

Reply to
Dand

"Dand"

** Bullshit.

The 50 Hz frequency is VERY accurate.

7 seconds per day loss can only happen if you have power outages.

Where are YOU ?

Back 'a Bourke ?

.......... Phil

Reply to
Phil Allison

A heavily loaded alternator goes low in frequency, I've repaired a few TTL based logic boards for the local power authority that trigger load shedding at substations when the frequency goes a few tenths of a Hz below 50 Hz. One tenth of a Hz over a day is nearly 3 minutes, in this day and age of privatised power generation and poor investment in new power stations for base load I would expect the frequency to drop in the middle of summer.

Reply to
Mark Harriss

While the 50Hz varies up and down during the day, due to load fluctuations, provided there are no power outages which result in loss of synchronization, the average frequency for the day is 50Hz exactly. This is why mains clocks maintain long term accuracy. During the day however they can be a few seconds out either way.

Most 50Hz clocks which run fast have poor filtering, which results in noise being counted as extra cycles, which cause them to run fast.

David

Reply to
David

Then you have a problem. The 50Hz is extremely accurate. My 50Hz mains clock (with 1/10sec display) does not loose 7 seconds in a year, let alone a day. It is by far the most accurate clock I have and have never had to reset it, except when the power fails. It is under 1sec / year accurate.

Dave :)

Reply to
David L. Jones

There are those who would say such projects are dumb, wasteful, nonsense....whatever. But they are incredibly instructive and just plain fun! :-)

Cheers.

Ken

Reply to
Ken Taylor

I must agree

Reply to
K `Sleep

Were they TTL or CMOS chips

My introduction to electronics was playing with 7400 quad nand gates and they were a big drain on power supply because they were TTL devices......

Reply to
John

I don't think the counting couuld be done with fewer than, 20 per digit so yeah huundereds would be accrate.

I've seen digital clocks with "flip-card" displays, driven by a motor and, I assume. a mechanism not all that disimilar to those used in odometers.

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   Jasen
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Reply to
Jasen Betts

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