Voltmeters are cheap, and have a great industrial aesthetic about them. This makes them prime candidates for hackers looking to do a clock build. [Brett Oliver] went down this very road, and built a very stylish timepiece along the way.
[Brett] initially wanted to go with 240-degree voltmeters, however the cost was prohibitive, so settled for the more common 90-degree models. New dials were produced by first sanding down the old dials, repainting in an old-fashioned off-white, and then applying the new graphics with inkjet transfer paper.
The attention to detail continues with the case. [Brett] aimed to build the clock with an old-school lab equipment aesthetic. A large piece of mahogany was crafted into the base. A clear plastic cover was sourced from eBay, which really makes the piece. Large buttons and toggle switches were chosen to complete the look.
On the electronic side of things, it’s all run by a PIC16F628A, which controls the voltmeters via PWM. Running with a 20MHz crystal, the PIC is not a great timekeeper. Instead, the whole show is synchronized to [Brett]’s master clock we featured a few years back.
Building a clock is a rite of passage for a hacker, and [Brett]’s example goes to show how craftsmanship can really pay off in this pursuit. Video after the break.
Nice build! I have the suspicion the power supply could do with better regulation: you can see both the minutes and hours meters jump a bit ahead whenever the second meter drops back to zero. The only reason I can see this happening is that the whole clock draws less current when the seconds meter drops to zero, and as a result the voltage rises a bit, causing the other meters to increase ever so slightly. Do these meters draw a lot of current?
Ok, Ill just say it. This is downright sexy.
There have been clocks and watches that have done this entirely mechanically, and its called a retrograde display. This is an instantaneous electrical triple retrograde clock.
I really, really, really like this! His aesthetic is excellent. I want one myself now
For anyone doing the clock challenge, I have an idea that I won’t have time or money to do: A Fibonacci clock- like binary, but with the Fibonacci sequence. If somebody wants a spreadsheet that shows how to count from 0-60 with 1,1,2,3,5,8,13,21,34, let me know.
Would be badass to do the whole clock entirely analog, with an Op-Amp as voltage stair generator for each of the 3 voltmeters. Could use this voltage stairs generator (explained by w2aew):
https://www.youtube.com/watch?v=Kqb5zcrgv7s
Adding an analog 4th indicator like this, for days, would be very challenging.
Would it even be possible to have a months indicator?
How about a 6th indicator for years, all analog?
:o)
It’ll be very hard to maintain any long term accuracy. It is bad enough in digital domain, but much worse in analog circuits as real life components aren’t ideal at all. Integrator accumulate errors – tiny amount of offset currents, non-linearity, leakage currents etc accumulate over long integrate periods can become significant.
On the other hand, most of these novelty “art” clocks aren’t meant to be accurate nor practical.
Huh?
You need 0-9, no smaller increments. You can take a cheap tuning meter from a fancy radio and put a new broad scale on it. Each number can be quite wide.
I get the impression that meters were used for readouts in some professiinal equioment, but I’m not sure. The first time I noticed the idea was in the RCA Hobby Circuit Manual from 1970. But later I saw it in magazines from a few years earlier.
Things were expensive, and crude. People would build frequency counters with RTL circuitry and be glad it counted up to 100KHz. Readouts were expensive, so they used a BCD display of light bulbs, 1-2-4-8 or just binary 1-2-4-8-16-32 etc. and did the math in their heads to get the total count. Meters fit in because there were endless cheap meters intended for consumer electronics, small and inaccurate, but useful since the readouts were broad.
It didn’t suddenly happen, there was an evolution over a few years. It took time for components to trickle down to the hobbyists, especially with low enough prices. So RTL became cheap as TTL rose, then ttl became cheap. Nixie tubes became available enough, and then LED readouts. There were also Numitron and 7 segment incandescent readouts around the same time. For tge hobbyist it took time, but consumer electronics almost suddenly went digital, endless gadgetry but also surplus for the hobbyist.
You made do, and for a relatively brief time using meters for readouts was viable. It wasn’t common because Nixie and LED readouts were too cool to avoid once prices came down.
As for the previous comment about using cheap digital panel meters, what’s the point? You only need broad readout, not precision.
He means, it would be very difficult to design and build an accurate, temperature stable analog oscillator that produces a time-varying voltage so slowly that it could be used directly as a clock simply by connecting it to an analog dial.
That’s because all the components leak nano- and microamps of current everywhere and have strange non-linear behaviors that depend on the phase of the moon for all we know. Things like air humidity and static electricity causing the clock to run out ten minutes a day because a capacitor changes value ever so slightly.
Let me fix the title for you.
Voltmeter clock in a great display case.