Afroman Makes A UHF Oscillator From A Potato

If you have ever worked with simple logic gates, there is a good chance that at some point you will have built a ring oscillator from a chain of inverters. With the addition of a resistor and a capacitor, you can easily make a square wave oscillator up into the megahertz range with standard logic chips.

[Afroman] received some rather special logic chips, from an unexpectedly named company, Potato Semiconductor. They specialise in making versions of common 74 series logic that smash the usual 100+ MHz barrier of the faster conventional 74 series chips, and extend their bandwidth up to over 1 GHz. Using one of their 74GU04 parts, he made a ring oscillator relying only on the stray capacitances of its gate inputs for its timing, and while he didn’t manage to achieve a GHz he did measure it at about 373 MHz. He took a look with a spectrum analyser, and as you might expect from a logic circuit found strong harmonics in the GHz range.

Now normally there would be no news in someone making a ring oscillator with a 7404. It really wouldn’t be a hack with a run-of-the-mill 74LS or 74HC part. But this Potato part is sufficiently unusual that it deserves a bit of attention in its own right. After all, we’re not used to logic chips that can work at those kinds of frequencies.

We’ve put his video below the break. Meanwhile, the Potato Semiconductor website makes for an interesting browse, and proves that there is plenty of life left in the venerable 74 series.

We’ve featured Afroman many times before, most recently with a simple power inverter circuit, and a small FM transmitter. We look forward to more from this prolific source.

18 thoughts on “Afroman Makes A UHF Oscillator From A Potato

    1. I don’t know if you are being sarcastic, but this battery setup has been on HAD before, and it basically doesn’t work. Because the electrolyte is shared between all the cells, only the first as last metal strip work as a (single cell) battery, all other strips are just one cell batteries that are short circuit, doing more harm than good.

  1. I feel bad for this guy. He had a Patreon page where some of the participants made fake pledges and used stolen cards. So he decides to make one of his (excellent) videos about filter capacitors pay-to-play for ~$1.50 on YouTube in order to get some funding – Then his audience completely loses their shit about daring to charge for a video

    1. >”Then his audience completely loses their shit about daring to charge for a video”

      But that is a shit move. It’s one thing to charge money for something you made, and another thing to sell the same thing over and over and over…

      That’s also why copyrights are fundamentally immoral – like putting a string on a coin to pull it back out of a vending machine. You do the work once and then attempt to benefit from the same effort multiple times. It’s a mode of business where you get paid arbitrarily many times without negotiation over what is a reasonable compensation, because the individual buyers have no means to estimate how much you’ve already been paid by other people.

      This is why services like Patreon exist in the first place. If you’re going to go back to abusing your viewership by pay-per-view, what the hell are you doing there??

      1. Why is it a shit move to offer something to somebody for money? Does creating a youtube channel involve signing some sort of contract stating that you will forever provide free content? I much prefer seeing him put out a video and charge for it such that I can politely decline to seeing him put out nothing at all.

    2. There was no hint / update vid of suddenly doing it the youtube red way and it also doesn’t work for German (and a lot of other nation’s) viewers, a main part of his viewers, as he states. The only option to show frustration about that: dislike button, since there is no option of commenting the video. Quite an understandable outcome. Shitty. But understandable.

  2. Anybody else realize that when photographers refer to their cameras in a self disparaging way, they call it a potato.
    “Oh, what kind of camera do you have?” “A potato.”

  3. Interesting, in the same setup (use dead-bug approach instead of Soic2DIP adapter) I tested SN74ALVC14 HEX SCHMITT-TRIGGER INVERTER, that is usually much slower then its x04 inverter and its unbuffered U04 version, and first thing I get is very unstable 360MHz, as chip temperature rise in sec or two drop from 309MHz to a much stable 202-204MHz.
    I also made some testings and benchmark on various logic IC’s and MCU’s during previous years and decide to make a project to shear them, check this link:
    https://hackaday.io/project/26268-benchmarking-of-mcus-soc-and-logic-ics

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