73 bit binary counter


Chronoscale is a 73 bit binary counter. It counts from 0 to 9,444,732,965,739,290,427,391 (2^73 - 1) at a rate of 1 million numbers per second. The counting is performed by 6 12-bit counter chips daisy-chained together with a 1 MHz clock driving the lowest counter input and the lowest LED. Each bit of output from the counters is connected to a bright yellow LED through a small drive circuit. The LEDs are mounted in a line on a sheet of lucite, connected to the driver board by a tangle of long thin 30 gauge wirewrap. Eventually, the board and display will be mounted in a frame to be hung on the wall.

The Numbers

Flashes 1 million times per second.
1000 times per second.
Visible flicker (30X per second).
Flashes once per second.
Once per minute.
Once per hour.
Every 1.5 days.
Every week.
Every month.
Every year.
Every decade(~9 years).
Every century.
Every millenium.
Every million years.
Every 10 million years.
Every 150 million years.
Chronoscale counts to nine sexillion four hundred forty four quintillion seven hundred thirty two quadrillion nine hundred sixty five trillion seven hundred thirty nine billion two hundred ninety million four hundred twenty seven thousand three hundred ninety one. It will take approximately 149.6 million years to carry out this task.

The 1st 14 LEDS appears to be continuously on. This is because they are flashing faster than the human eye can perceive (60X per second up to 1000000X per second). The 15th LED can be seen to flicker (~30Hz). To the right is a table of select LEDs of interest.

Note, these numbers describe the periods of the named LEDs, which is to say that they indicate the amount of time it takes for an LED to go through a full cycle of being off, turning on, and being on the brink of going back off again. To calculate the time it will take from the start of the count to a particular LED coming on for the first time, divide these numbers by two. To find out how long the counter has been running, you'd add together all of the 1/2 periods of the LEDs that were lit at that moment.

I think it is interesting to note that I would be lucky to see, were I to plug this device in now and let it run continuously for the rest of my life, the 51st or 52nd LED come on.

Also of note is that during the full 150 million year period of the count, each LED is on exactly half of the time.

Some Pictures

[Lone board]
Finished board without display attached.

[Top view of board with display installed.]
Top view of board with display installed.

[Board propped up with display installed.]
Board propped up with display installed.

[Angled view of the display panel.]
Angled view of the display panel.

[Moving picture]
Picture of the display taken by moving the camera. Note the characteristic binary count pattern. One more LED than can be seen to flicker with the human eye is visible in this case.

Future work

There are three things I'd like to do with this projects now that it has attained this state.

The first is to build a case for it so that it can be hung on the wall. Currently, the board itself and the display are only attached by those flimsy wire-wrapping wires. The whole thing needs to be mounted better.

The second is to add an overlay piece of lucite that gives some indication of what time scale each of the LEDs flashes on. This will help bring the object into better perspective for those unfamiliar with the binary count pattern. It will also make the time scales easier to understand without the aid of a calculator.

The third thing I'd like to do is add to the circuit some way of remembering its count without the power attached, and subsequently resetting itself to that count when plugged back in. Currently, a power outage will reset the circuit to the beginning. Not a useful condition. I'll either do this with circuitry that stores a charge and disables the LED display and oscillator during poweroff (sort of like an uninterruptable power supply), or I'll add a PIC to it that keeps track every so often and runs the count back up using the multiplier buttons I put on the board. The multiplier buttons were put there so that I had some way of running through the whole count and jamming on all the LEDs to test if my power supply was truly adequate for its purpose.