Watts on the bench #7 – A chronulator

Back in July 2011 Hayden, VK3FRST, Ash VK3FASH, and I spent some time at the old VK3SCG station located in Cleve Cole Hut at Gilwell Park. We were there providing an amateur radio activity for the Communications Patrol Activity Camp.

During this camp Hayden passed a kit to me known as The Chronulator. The Chronulator is from ShareBrained Technology and is described on their website as “a clock that uses old-school analog, mechanical meters to show the time. . . The kit is great if you want to learn how to solder electronics, or you want to give a unique gift to a technology geek.”

The kit then sat on the shelf in my shack until last weekend when, in a fit of nostalgic activity, I warmed up the soldering iron and built it.

Construction was straight forward with excellent instruction available here. Once I had assembled the board I fitted the batteries, performed the calibration and then struck a problem. I couldn’t get the minutes dial to set. It moved hard left and right during the calibration but then just sat in the middle.

I traced the problem and found that pin 13 of the micro controller was shorted to ground due to a manufacturing defect on the PCB. The top pad for pin 13 had a small amount of copper that had not etched away creating a bridge to the top ground plane of the PCB. It’s the kind of thing that happens maybe 1 in 1000 boards and it would normally be picked up during a visual inspection. This one had got through and, to be perfectly honest, I didn’t check the board before assembly. I cut through the rouge copper with a knife and then the minutes meter behaved correctly.

All that is left to do now is make a suitable housing for the two meters. I want something unique and stylish so I can place it on my desk at work and it will attract positive comments and curiosity.

Thanks Hayden.


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