OT: NO IC's :-)


Build An Insanely Complicated Transistor Clock


can i have one with its own oscillator. i dont like the idea of sync to mains 60Hz.

and could that be less components.



A 50-Hz mod is available:



The curious specification on the 60Hz main is that the frequency may vary slightly throughout the day, but the long term stability is very accurate.



While it's been true for decades that 60Hz power in the US has a very high low-term accuracy that may no longer be the case in the future. I've see this story referenced several times in the past few months. It's very disturbing to me as I've designed and built a few clocks that depend on accurate 60Hz.

OTOH, you can buy TCXO (temperature compensated crystal oscillators) for a few dollars that have infinitely better short term accuracy (1 ppm over a huge temperature range) with low aging rates and initial accuracies to rival the long-term accuracy of the 60Hz power grid.

Still, there's nothing like an old-fashion 60Hz motor-based clock that you can refer to when trying to figure out how long the power has been out in your house.

Edited: 5 Nov 2011, 11:26 a.m.


Historically, those synchronous-motor clocks were the reason for accurate 60Hz. The inventor, a guy named Henry Warren, had this great idea on how to make an accurate electric clock but then realized that the 60Hz from the power company wasn't always 60Hz. Rather than give up, Warren sold the power companies fancy clocks combining one of his electric motors and an accurate mechanical movement to help them regulate frequency: Telechron Master Clock


There is a good reason to have the 50 or 60 Hz accurate: Power systems are networked and need to in sync when this shall be without any programs: Imagine a power plant of a few megawatts working with just the wrong frequency or phase compared to the power line it is feeding!


Sure, power plants need to sync to the 50Hz or 60Hz grid before feeding power into it, so they need short term accuracy of maybe 0.01%. However, other than time keeping there's no reason that they need to have good long-term accuracy.

Getting rid of long-term accuracy on the power grid will instantly obsolete millions of clocks and devices with embedded clocks that rely on the 50Hz/60Hz line.


Thanks for pointing that out and the link, it's interesting history.


With the shutdown of several nuclear plants in Germany, the frequency of the electrical grid has become rather unstable - in fact the drift is that huge, most older wind and solar power stations will do an emergency shutdown once in a while. They all have to be upgraded to a modern (more forgiving, working on a wider frequency range) DC/AC converter.
The 50Hz based clock is probably dead as of now.


The 60 hz. frequency is maintained simply by the rotational speed of the generators. (3600 RPM => 60 hz.) The RPN varies slightly as load varies during the day. The power company has devices that simply count revolutions, and during the wee hours of the morning when load is low they either speed up or slow down the generators enough to correct the clocks once every 24 hours.


I recall in my parent's house several clocks sync'd to (our mains frequency of) 50Hz.


Most of my watchees and clocks recrive the NIST (US) time signal.
One even makes several readings and digitally adjusts it's rate. Sam


Nice that it is sold as a kit, I am a big fan of nixie clocks, my last nixie clock used a very early clock chip that I demultiplexed and converted the 7 seg code to BCD for the nixie drivers. I wanted to build a electromechanical one using stepping relays but, stepping relays seem very hard to come by now. I saw a web site for one built from vacuum tubes. The most unusal one I have seen using neon tube ring counters to keep track of time.


I just had to dig out my Heathkit GC-1005 - still works like a charm. It is centered around the famous Mostek MK5017 chip and was a wonderful, yet affordable kit sold between 1973 and probably 1975 or 1976.

I guess this is the HP 35 for clocks:

Have a great weekend,



I have a brand new MK5017 sitting here on my desk just waiting for my next clock project, maybe I will use some of my 7 segment nixies with it. I built my first digital clock in 1975 it used LED displays,and it still operates fine. It was built on a project board sold by Radio Shack, and the parts to build it cost be about the equivalent of a weeks salary.


What is the date code of the "brand new" chip?



7318 it still in the original Mostek package, I only removed the paper label off the top to look at the chip, I have not taken it out of the package yet. Chip is a white ceramic, side brazed 28 pin dip with gold plated pins and lid over the chip well info off top of chip

MK5017AN P
7318 A

Aw, that is great! And in perfect shape!

I wanted to build a Heathkit transceiver soooo badly--and I wanted to build a Heathkit oscilloscope, too. But alas, they went out of business before I could get to that point.

I had a strong Ham radio interest as a kid in the late 70s. It seemed as if *every* elmer ham had built a digital clock--not unlike the Heathkit you have--and set it to "UTC".

Good memories. Maybe someday I'll buy an SB-101 just because...(god, I remembered the model name! Just checked google! Youthful memories are so strong...)

Edited: 6 Nov 2011, 9:02 p.m.


They never totally went out of business (see http://heatkit.com ) but they quit making kits in '92. (They are starting back into the kit business now.)

I have to disagree with their reasons for quitting. They said kitbuilding was no longer possible for the hobbyist because of SMT, while the truth, especially back then, was that most things could still be done in thru-hole, and there are plenty of areas of electronics that can still be carried out that way today. As for compactness, many of the products were, as I used to like to say, packed tight with empty space. For those, whether TVs, stereos, non-mobile amateur-radio equipment, etc., making it really small was irrelevant.

Heathkit also said the kit builder could no longer save money by assembling it themselves; but saving money was not the issue with most of the kit builders in my observation. If the same thing could be gotten in a non-kit form from another company, they were frequently paying more to get the same thing in a kit version, and they knew it; but they wanted the experience that went with it. Although I had about 20 Heathkit products at one time, I never thought of Heathkit as being the way to save money. They did however have some rather unique products I didn't know any other way to get. They could have taken advantage of that niche-market situation.

The most complex Heathkit product I ever assembled was a compact portable 20MHz dual-trace triggered oscilloscope which could run on an internal battery. It really was too much. I got 80% or more of the way done and basically gave up and let it collect dust for a few years before I got it back out and decided to finish it.

There are some amateur radio kits today from other companies, and it looks like Heathkit has decided to get back into it. It will be interesting to see what happens, since a company is basically the people, and all the ones who were there in the 70's are undoubtedly gone.

Edited: 6 Nov 2011, 9:59 p.m.


They were a great company, I can't imagine that the reinvention of it will be nearly as good. I had a part-time job in college working in a neurophysics lab run by a professor who loved Heathkit. Some of the work I did there was to build these kits for the lab.

They also came up with the incredible OC-1401 5-level RPN navigation calculator that is one of the most creative machines I know of from several standpoints: functionally (full scientific calculator and navigation and clock/stopwatch), electronically (3 communicating microprocessors and an interesting mix of power options) and a colorful, cool looking design with clicky keys too!

Edited: 6 Nov 2011, 11:48 p.m.


That's suppose to be http://www.heathkit.com/ not http://heatkit.com


Woops, my apologies. That comes from being too tired when I wrote.

Silly story about a Heathkit from my last place of work, in the late 1980's: The Heathkit AD-1309 noise generator looked like the perfect fit for a need we had, and it was cheap too-- maybe around $40 IIRC. I think it was even on sale. We were going through a temporary financially tight period, so we had to write up a justification for every piece of equipment we wanted. I wrote up something short for this, not wanting to take much time since it was so cheap anyway, and it was so simple that the labor to put it together would be minimal. The general manager came back to our office and said he needed me to write up a little more detail about <bla bla bla...> There was yet another iteration of this, such that the company cost for my time spent justifying it and the general manager's time spent trying to over-analyze because of the tight finances was considerably more than the cost of the noise generator itself.

Edited: 7 Nov 2011, 4:18 a.m.


So the real 'noise' was generated in-house. ;-)


I built a lot of Heathkits in the 1970s: scopes, meters, generators, the transistor tester, power supplies, clocks, stereos, the microwave oven, and even a Heathkit all-metal power strip, which I still have. The kit business has evolved and the heir to the Heathkit throne (in my mind) is Sparkfun (www.sparkfun.com) in Boulder, Colorado. They offer a bunch of great kits, parts, and are very youth-oriented. At this year's Maker Faire in Silicon Valley, they had a booth with about 30 soldering stations where kids sat intensely building their kits, with and without parents' help.

The Maker ethos is this century's version of the electronic kitbuilder. Check out Sparkfun's every-Friday new-product videos. These guys know how to market on the newfangled "Internets." They set the bar for the new Heathkit as far as kitbuilding is concerned.

Edited: 7 Nov 2011, 9:41 a.m.


I agree that Make, Sparkfun, Adafruit and the like do a good job at generating enthusiasm. I've been to a Maker Faire (in NY) and seen people soldering at the Sparkfun booth and subscribed to Make magazine for a while too.

What I find different from the Heathkit of old is the near total lack of theory behind the projects. Make magazine, for example, ncourages you build stuff without explaining really anything in the way of theory. Heathkit always had a good description of the theory and circuits in their kits they were very focused on education and became just an education company.

I suggest that Parallax and Revolution Education (PICAXE) are more the heirs to the Heathkit throne. They do a great job of teaching, especially Parallax.


Edited: 7 Nov 2011, 3:06 p.m. after one or more responses were posted


Thanks for the other ideas Katie! This should be fun sharing the excitement with my grandchildren.


I kept a few Heathkit catalogs over the years, the earliest being from when they actually published the schematics in the catalog. Later of course they got too complex. Imagine putting an oscilloscope schematic there in the catalog. Mine was 24"x36" with rather small print IIRC, printed on both sides.


They never totally went out of business (see http://heathkit.com ) but they quit making kits in '92.

Yes, and they sold ham equipment to the end. One would need to be younger than about 35 to have missed the Heathkit ham era. I had an order for a low power ham kit in to them when they dropped out of the market, cancelling my order.

Heathkit also said the kit builder could no longer save money by assembling it themselves; but saving money was not the issue with most of the kit builders in my observation.

Saving money was certainly the most important advantage to a Heathkit purchase for me. There was never anything particularly clever or innovative about Heathkit gear, except the associated construction manuals. Plus, whatever resulted from the built-by-customer process was extremely variable in quality, which makes purchase of used Heathkit gear a big gamble.

I would have liked (even today) the Heath H-11 (their version of the PDP-11) computer system. Now that was expensive!

There are some amateur radio kits today from other companies, and it looks like Heathkit has decided to get back into it.

I wouldn't bet on anything substantive coming from a Heath re-start. The majority of Heath's real corporate direction was toward the amateur radio market. I always questioned the appeal their other junk had for their customer base. Today's heir-apparent for amateur radio gear in fact, not just potential, is
Elecraft Company in California, which has been marketing several sophisticated amateur radio transceiver kits using through-hole construction (K1, K2, KX1), a world-class performance semi-kit (K3), along with various accessories. A new portable transceiver (KX3) is expected soon that is, IMHO, the most interesting electronic device I've seen in 45 years as an amateur radio operator. Construction and operation manuals are available for free download and are generally superior to the excellent and legendary output from Heath in its best days.

Edited: 7 Nov 2011, 10:54 a.m.


Always happy to meet another HP calculator loving ham. I'm still a complete newbie myself, but I've taken to the hobby like a fish takes to water!

And yes, I want a KX3 like nobody's business :)

73 de NF6Q


Always happy to meet another HP calculator loving ham.

I'd been a ham for quite a few years by the time I used six weeks (!!!) of take-home pay as a Navy lieutenant(j.g.) to purchase my first HP in 1977...the newly-introduced HP-67 (which is today out for card reader repair). That was a great machine to start my 35-year collection!

It was one of my two "major" purchases made while in military service. The other was a new 1976 Heathkit HW-101 ham transceiver kit that took me four months to build due to my having almost non-existent free time. The money-saving aspect of Heathkit ham gear was its most important advantage to me, at a time when Navy junior officers got paid less than unskilled civilian laborers performing welding-spark fire-watches in a shipyard.

It's really odd today to recall the purchase of a handheld calculator qualifying as the major purchase made during a period of five years service. :-)

And yes, I want a KX3 like nobody's business :)

I'll wait about six months after introduction just to let any hardware issues settle out. Until then, there's my 11-year-old K1.

73 de NF6Q

I've seen you on the
Elecraft List.

73 de KK5F

Edited: 8 Nov 2011, 12:02 p.m.


My Heathkit clock like this, built in the mid-60s, sits by my bed to this day.


My Heathkit clock like this, built in the mid-60s, sits by my bed to this day.

Don't you mean the 70's... as the GC-1005 was introduced, IIRC, in 1972. I was a tech in HEC #42 during the 70's and remember when it came out - the first kit to have the crazy Molex staggered pin IC socket strips. Oh, brother, the hours I spent resoldering those monsters.


I built one of their darkroom timers sometime in the late 60's/early 70's. It was the first time I ever soldered anything and it used point to point connections on terminal strips, it even had a vacuum tube in there for voltage regulation. It didn't work right after I finished of course and I sent it to Heathkit for repair. I'm not sure if it came back with a label telling me which tech did the work but I'll bet it was lucky #42! :)

I've built many Heathkits since then and never had to bother #42 again, but it was good to know that he was there if I needed him!

Randy, How long did you work there?


Edited: 10 Nov 2011, 5:30 p.m.


#42 was the store number in suburban Philadelphia, not a tech at Benton Harbor. I worked there from 72 to the summer of 1977, when I got my first job in engineering. I was the RF (ham,CB,R/C) and general kit guy, another did just stereos, another just televisions.

It was was a great place and after '77, I did weekend work for a while fixing the "dogs" the new guys couldn't or did not want to get working. It really did build great trouble-shooting skills because just about anything could be wrong. Swapped resistor values was always my favorite... had one that I remember that had every 1k and 10k resistor swapped.

After Zenith acquired them, I remember seeing for the first time the H89 terminal - with the factory assembled processor board. When I asked why it was already built, I was told it was because Heath felt it could not be assembled reliably by customers due to the density. I thought to myself "the goose is dead". As in the goose that laid the golden egg of kits. What's the point of a kit that's not a kit?

Fast forward a few years later, I stopped by the store one day only to learn that everybody I knew was gone, as in fired. They shipped the inventory back to the factory and that was it for #42. Today, the building is a local family pizzeria.

Edited: 11 Nov 2011, 8:09 a.m.


Could have been the 70s, I guess. I thought I remembered that clock by my bed when I was a summer student at a particular place in the 60s. I worked there full time in the 70s, so maybe that is what the rememberance SHOULD be!

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