Old-school frequency counter

Edge-Mounted Meters Give This Retro Frequency Counter Six Decades Of Display

With regard to retro test gear, one’s thoughts tend to those Nixie-adorned instruments of yore, or the boat-anchor oscilloscopes that came with their own carts simply because there was no other way to move the things. But there were other looks for test gear back in the day, as this frequency counter with a readout using moving-coil meters shows.

We have to admit to never seeing anything like [Charles Ouweland]’s Van Der Heem 9908 electronic counter before. The Netherlands-based company, which was later acquired by Philips, built this six-digit, 1-MHz counter sometime in the 1950s. The display uses six separate edge-mounted panel meters numbered 0 through 9 to show the frequency of the incoming signal. The video below has a demo of what the instrument can do; we don’t know if it was restored at some point, but it still works and it’s actually pretty accurate. Later in the video, he gives a tour of the insides, which is the real treat — the case opens like a briefcase and contains over 20 separate PCBs with a bunch of germanium transistors, all stitched together with point-to-point wiring.

We appreciate the look inside this unique piece of test equipment history. It almost seems like something that would have been on the bench while this Apollo-era IO tester was being prototyped.

Continue reading “Edge-Mounted Meters Give This Retro Frequency Counter Six Decades Of Display”

NTP, Rust, And Arduino Make A Phenomenal Frequency Counter

Making a microcontroller perform as a frequency counter is a relatively straightforward task involving the measurement of the time period during which a number of pulses are counted. The maximum frequency is however limited to a fraction of the microcontroller’s clock speed and the accuracy of the resulting instrument depends on that of the clock crystal so it will hardly result in the best of frequency counters. It’s something [FrankBuss] has approached with an Arduino-based counter that offloads the timing question to a host PC, and thus claims atomic accuracy due to its clock being tied to a master source via NTP. The Rust code PC-side provides continuous readings whose accuracy increases the longer it is left counting the source. The example shown reaches 20 parts per billion after several hours reading a 1 MHz source.

It’s clear that this is hardly the most convenient of frequency counters, however we can see that it could find a use for anyone intent on monitoring the long-term stability of a source, and could even be used with some kind of feedback to discipline an RF source against the NTP clock with the use of an appropriate prescaler. Its true calling might come though not in measurement but in calibration of another instrument which can be adjusted to match its reading once it has settled down. There’s surely no cheaper way to satisfy your inner frequency standard nut.

Easy Frequency Counter Looks Good, Reads To 6.5 MHz

We were struck by how attractive [mircemk’s] Arduino-based frequency counter looks. It also is a reasonably simple build. It can count up to 6.5 MHz which isn’t that much, but there’s a lot you can do even with that limitation.

The LED display is decidedly retro. Inside a very modern Arduino Nano does most of the work. There is a simple shaping circuit to improve the response to irregular-shaped input waveforms. We’d have probably used a single op-amp as a zero-crossing detector. Admittedly, that’s a bit more complex, but not much more and it should give better results.

Continue reading “Easy Frequency Counter Looks Good, Reads To 6.5 MHz”

Improving A Cheap Frequency Counter With GPS

Frequency counters are useful tools for anyone that finds themselves regularly working with time-variant signals. There are a huge range available, from cheap eBay specials to expensive lab-grade hardware. [itakeyourphoto] had a counter on the lower end of the cost spectrum, and decided to make some improvements with the help of GPS (Youtube link, embedded below).

The fundamental weakness of a cheap frequency counter is usually the internal reference against which all other signals are measured. The more accurate this is, the more accurate the counter will be. [itakeyourphoto] determined that a great way to generate a reasonably good reference frequency was by using a uBlox GPS module. Once locked on to satellites, it can use a numerically controlled oscillator to output any frequency up to 15MHz with good accuracy.

The cheap frequency counter in question used a 13 MHz internal reference, so the uBlox module was programmed to match this. [itakeyourphoto] reports that it compares favorably to his higher-end GPS-disciplined oscillators, displaying very little drift or other aberrations.

We see plenty of clocks using GPS for its accurate time, but we’ve seen projects that attempt to go even further than that, too. Video after the break.

[Thanks to jafinch78 for the tip!]

Continue reading “Improving A Cheap Frequency Counter With GPS”

Hacking A Cheap EBay Frequency Counter

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!]

Continue reading “Hacking A Cheap EBay Frequency Counter”

Very Simple PC Frequency Counter Works Up To 100MHz

We all use 74 logic in our projects as general purpose logic interfacing glue. These chips have become as ubiquitous as a general-purpose op-amp, or even as passive components. In most cases we’re not demanding much of them, and power requirements aside an original 74 chip from the dawn of the series could probably do the same job that we’re putting a more modern variant to work on.

It is easy therefore to forget that 74 logic is a field that has seen continuous improvement and innovation reflecting the developments elsewhere in electronics, and the most modern 74 versions hide some impressively high specifications.

A good example comes via a project from [Scott, AJ4VD], a very simple frequency counter that uses a single 74 series chip at its business end, and counts to over 100MHz. The chip in question is a 74LV8154 dual 16-bit counter which he is using as a prescaler to deliver a rate more acceptable to an ATMega328 microcontroller that does the counting. As he points out, the accuracy of a frequency counter is only as good as its gate timing, and he ensures as accurate a seconds-worth of pulses as he can with a 1PPS signal derived from an inexpensive GPS receiver. The 328 makes its counting available to a host computer via a serial port, and can be easily read through a terminal. He’s built it dead-bug style on a piece of unetched PCB, on which the simplicity of the circuit is evident.

There was a time when a project like this one would have required multiple integrated circuits including a probably quite expensive purpose-built prescaler. Cheap glue logic has now advanced to a stage at which it can be done instead at commodity prices, and we like that.

We’ve featured a few 74-series counters before, including this old-school one and this one also using a 74LV8154.

Hackaday Prize Entry: A Minimal ATtiny Voltage And Frequency Counter

Sometimes when you build something it is because you have set out with a clear idea or specification in mind, but it’s not always that way. Take [kodera2t]’s project, he set out to master the ATtiny series of microcontrollers and started with simple LED flashers, but arrived eventually at something rather useful. An ATtiny10 DVM and DFM all-in-one with an i2c LCD display and a minimum of other components.

The DFM uses the ATtiny’s internal 16 bit timer, which has the convenient property of being able to be driven by an external clock. The frequency to be measured drives the timer, and the time it returns is compared to the system clock. It’s not the finest of frequency counters, depending as it does on the ATtiny’s clock rather than a calibrated crystal reference, but it does the job.

The results are shown in the video below, and all the code has been posted in his GitHub repository. We can see that there is the basis of a handy little instrument in this circuit, though with the price of cheap multimeters being so low even a circuit this minimal would struggle to compete on cost.

Continue reading “Hackaday Prize Entry: A Minimal ATtiny Voltage And Frequency Counter”