eBay is a wondrous land, full of Star Wars memorabilia in poor condition, old game consoles at insane markups, and a surprising amount of DIY electronics. [TheHWCave] found himself tinkering with a common frequency counter kit, and decided to make a few choice improvements along the way (Youtube link, embedded below).
The frequency counter in question is a common clone version of [Wolfgang “Wolf” Büscher]’s minimalist PIC design. Using little more than a PIC16F628 and some seven-segment displays, it’s a competent frequency counter for general use. Clone versions often add a crystal oscillator tester and are available on eBay for a fairly low price.
[TheHWCave] found that the modifications were less than useful, and developed a way to turn the tester components into a more useful signal preamp instead. Not content to stop there, custom firmware was developed to both improve the resolution and also add a tachometer feature. This allows the device to display its output in revolutions per minute as opposed to simply displaying in hertz. By combining this with an optical pickup or other RPM signal, it makes a handy display for rotational speed. If you’re unfamiliar with the theory, read up on our phototachometer primer. If you’re looking to modify your own kit, modified firmware is available on Github.
We’ve seen other eBay kit specials modified before. Being cheap and using commodity microcontrollers makes them a ripe platform for hacking, whether you just want to make a few tweaks or completely repurpose the device.
[Thanks to Acesoft for the tip!]
5 thoughts on “Hacking A Cheap EBay Frequency Counter”
A helpful addition that I find too few counters have are a total count and a rolling count
So often I just want to count the total number of events or counts per second and have to get creative with integration and such
That’s all just firmware. Jump into it!
I found that a modified pedometer counted turns very effectively for a coil winder build.
Back in the days, I have modified calculators by wiring into the = button which executes the last operation repeatedly. It is not limited to just adding 1. :) So you can use it to count distance by revolution. Speed of the calculator is the imitation.
Thanks for sharing!
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