Frequency Counter For $10 Worth Of Parts

March 14, 2011 by Mike Szczys 10 Comments

[Scott] built this frequency counter using less than $10 in parts. It’s set up to meter frequencies in megahertz which is fitting since he’s planning to use it with his radio hardware experimentation. But we would find it useful too because our cheap multimeter only reads up to around 4 MHz.

He’s using an ATmega16 that he had on hand but it has features way beyond the specs for the device. He speculates that an ATtiny2313 would easily work in its place. The microcontroller is mostly used to drive the multiplexed 7-segment display after reading the frequency values from the 74LV8154 counter chip that he is using. He doesn’t have a full schematic for the device, but there is a hand drawn diagram for using the frequency counter; the rest should be easy to piece together. Looking at that circuit we don’t think it would be too hard to make this a manual-ranging frequency counter to give you more use out of the dedicated device. Check out [Scott’s] demonstration video which is embedded below the fold.

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Nixie Frequency Counter Gone Timepiece

November 12, 2010 by Mike Szczys 25 Comments

[Windell] of Evil Mad Scientist Laboratories took an ancient Nixie tube based frequency counter and converted it into a clock. The unit he got his hands on is an HP model that was still in great shape. He’s using an internally generated one second pulse as the clock signal, but some modifications are necessary to display time. That’s because the frequency counter is base 10 and clocks use a quirky combination of base 60 and base 12.

It wasn’t too much of a problem to rig up a system to track minutes and seconds. The tens digit for each is monitored by a couple of AND gates that he added to the mix. When they detect a ‘6’ the digit is reset and a pulse increments the next digit as the carry. This is more difficult to accomplish with the hours though. Minutes and seconds count from 0 to 59 but hours don’t start at 0. Instead of over-complicating the logic [Windell] used a bit of slight-of-hand. The Nixie tubes for the hours have been rewired so that when the counter is at 0, the filament in the shape of a 1 lights up. No difference in logic, just a translation that makes them display one digit higher than the actual count.