Turning a rubidium standard into a proper tool

Rb

You can find rubidium frequency standards all over eBay and various surplus dealers. They’re actually quite interesting devices, able to generate a 10 MHz sine wave with enough precision to be a serviceable atomic clock. While these standards can find themselves very useful in a lab, they’re only a component, and not a working-out-of-the-box device. [Gerry] decided he would fix that, turning his rubidium standard into a proper piece of bench equipment, all in a single afternoon.

[Gerry]‘s first step was finding a proper enclosure for his new piece of equipment. Most of the time, choosing an enclosure is practice in the art of compromise. This time, though, [Gerry] found the perfect enclosure: an old piece of video distribution equipment. On the back of this box, there are a ton of BNC plugs, perfect for attaching to random lab equipment and feeding them a signal from the rubidium standard.

After going through the video circuit and changing the 75 Ohm outputs to 50 Ohms, [Gerry] wired up an eBay power supply, fan, and a small circuit with an 8-pin PIC to complete his new tool. The rubidium standard does get freakishly hot, but hopefully mounting it to a large aluminum box with a bit of cooling will keep all the added electronics in working order.

[Gerry] did all this in just under 5 hours. An impressive feat, given that he probably spent that much time editing the video, available below.

Comments

  1. Can you please tag al articles that contain *NO* writeup and only video with some easy tag like “videoonly” so that those of us who prefer to read at our own pace and not watch/listen as somebody else’s glacial pace (or just have no time to watch a video) can skip over them easier?

    • Rob says:

      Yes, please. I won’t watch videos in 99% of cases. If there’s no text writeup, it’s of no interest. Sad, as in this case, I would have been interested to read a write-up. Making such an annotation would be greatly appreciated.

    • djdesign says:

      I hate to sound like a grumpy old man but I agree. I’m not a fan of most youtube submissions. They are always way, way too long (edit…edit…edit). I will never watch a 1 hour 16 minute video with content I could have gathered in a few minutes from a written form. I will barely watch a 5 minute video.

    • Pun says:

      This.

    • BillP says:

      I second the motion. Here I thought I was alone in my distaste of video only posts….

      • Rob says:

        Oh gosh no. You’re most certainly not alone. It’s followed immediately on my list of “crap that websites do that makes me want to kick puppies” by sites that show things in a series of steps where each step is it’s own frigging page (yahoo news, instructables, etc…). No, I’m not going to watch the video unless the article convinces me that it’s somehow useful, no I’m not going to click through 10 “next” buttons to see the next item on your stupid list, no no no no no. Get off my lawn!!! Gaaaaaaaaaaahhh!!!!!!!!

        • djdesign says:

          LOL! Yes, especially because their ad servers always take an impossibly long time to respond and you’re stuck there waiting and waiting for page 7 to load.

          All that whining aside, just based on the photograph, this is a neat hack. Props to this guy for making his own precise time standard. It looks like a quality build and I hope he ends up providing a timebase for a nixie clock in every room …

        • Sprite_tm says:

          Just curious, are you always against paginated articles? On spritesmods.com I tend to paginate my articles, but it’s mostly so each part will stand on its own, like a new page in a book. I have to admit, it helps with advertisement income too, but I’m thinking of doing away with it if it really infuriates people; I’d rather have a website that people read than a website making stacks of money from unhappy people.

          • andres says:

            I’ve been to your site quite a few times and in my opinion you have enough knowledge to share to justify paginating your articles. Your articles are top notch.

          • Karl says:

            On spritemods.com the paginating is much more logically organized with every new chapter on a new page, unlike Instructables for example, where you have to click “Next” 10 times to find out how to blink a LED with an Arduino.
            Besides, when you are able to boot Linux using a hard disk controller, you can do whatever you want :D Keep up the good work!

          • Greenaum says:

            As long as each page contains about a page full of information. I don’t mean 1K of text or any fixed amount of words. But if the page, pics and all, is about as full as it needs to, that’s good. I suppose you could aim for 2 – 4 screen-heights’ worth of scrolling.

            Your site’s always been great in my experience. It’s stuff like (especially) those syndicate-ad-farm-godknowswhat things that clutter up the web these days. that annoy me. The ones with the lists. Yeah, you know! 1 paragraph and a picture, or worse, 1 sentence and a picture, is NOT a page!

            Use your judgement. You do okay now. It’s like setting out paragraphs, a page should contain one idea, or one sub-idea of a larger article. For projects like yours, Sprite, I’d say 4 – 6 pages per project.

            Of course, there’s always the experiment… do a few projects in both ways, single-page and multi-page versions. Offer links to both, see what the stats say people are choosing.

      • Blue Footed Booby says:

        Every time I find a tutorial on something I really want to do only to find out it’s a series of ten minute videos instead of text with pictures, I die a little more inside. Not only do I not have the patience for video paced to the lowest common denominator (read: someone without ADD), I have *terrible* auditory memory. By the time you finish a sentence, I’ve forgotten the first half. On the other hand, I have *excellent* memory for what I read. Yet most of the time the video doesn’t even have subtitles. :C

    • carlitos chatran says:

      Completely agreed. These video thingies are getting really annoying. What are we, 6-year olds who cannot read and need to be told everything verbally? I do not ever see these videos, but waste my time and bandwidth clicking on the links from HADay… TAG them video only, please.

  2. loans says:

    “and a small circuit with an 8-pin PIC to complete his new tool.”

    How is this useful information? What IC?

    • Nova says:

      A PIC by the company Microchip, the one he uses is kinda irrelevant since he just programs it to blink an LED on an active low signal.. I don’t even understand why the blinking is necessary, a very simple transistor circuit and Red-Green LED could replace this.

  3. joq says:
  4. thioden says:

    Maybe I’m missing something, but shouldn’t he also replace the actual BNC connectors with 50 ohms ones instead of just changing the resistors?

    • LongFist says:

      Sometimes part of the hack is doing something that reduces waste. What would he do with a pile of 75-ohm BNC connectors? Maybe he felt like getting the job done in 5 hours (or fewer) rather than wait a few days for the parts delivery, etc. Who knows what drives these people (who achieve things) to do what they do? But I applaud him for it – it’s that level of attention to detail that makes (or breaks) a great project!

      Excellently done. Now all we need is a comprehensive write-up…

    • Myself says:

      Take a look at a 50-ohm BNC next to a 75-ohm one, the differences are pretty stark. Then ask yourself if you’ve ever seen a 75-ohm one in the wild.

      In my experience, most video equipment uses 50-ohm BNC connectors with 75-ohm cable and 75-ohm signals on them. It’s goofy and awful and it’s part of why I’ve never been able to take analog video seriously.

      Video distribution amplifiers are usually pretty darn clean through 6MHz, the bandwidth of an NTSC signal, so they’ll pass a 10MHz sinewave with minimal modification or perhaps none at all.

      If I had to guess about the function of a PIC, it’s probably to provide a PPS heartbeat or something. Often the PPS signals on these are just a few ns wide, and you need to stretch the pulse before you can drive an LED with it. I have neither the time nor the bandwidth to sit through an hour-long video and find out. ;)

    • technoneet says:

      There is very little signal integrity degradation of not replacing the
      75 ohms BNC with 50 ohms. The signal is 10MHz sine wave, so we don’t
      have to worry about the upper harmonics. You are look at a tiny
      discontinuity at the connector. So it is like 2cm for a signal with
      wavelength of 30 meters.

      To use a car analogy, it would be like the effect of a tiny pebble on
      the road against a monster truck with 2 meters diameter tires.

      I would be more worry about how that signal was fanout to each of the
      BNC connectors. It would cause a lot more signal quality issues if not
      done correctly. Not worth my time to watch the video to find out.

  5. regveg says:

    I really enjoyed this video – I don’t usually watch many but I enjoyed the journey through the process. I’m looking forward to seeing it with the heat sink on the front & I’m definately going to enjoy watching more from the same guy.

    The thing I don’t really like much is the grumpy old fart attitude above. If you don’t like videos dont watch them. As for having a “video only” indicator on the post I’m all for it – it’ll save you all 500 milliseconds of time working that out for yourself and mean you wont spend valuable seconds polluting the comments section with whine. Maybe you should make your own hackaday “elite” site where you can agree a set of standards for what posts should contain and then rigidly conform to them..

    • LongFist says:

      >> The thing I don’t really like much is the grumpy old fart attitude above.

      Agreed. Some of these people post as if their time was incredibly valuable, but they had *NO* control over how they spend it. It’s almost like they *MUST* watch the video if it’s posted; they *MUST* read every hack that gets posted; they cannot figure out how to skip, abort, or navigate away from the videos (or other hacks) by themselves. Amazing!

      But they *CAN* always find the time to comment negatively, to try and pour poison on others’ efforts. You’d think they paid a fee to come here, watch this, have their intelligence insulted, and whine about it. I guess they haven’t encountered the sheer enormity of the interWebz: They can always fire up their favorite search engine and find an alternative “out there” someplace. THIS site would benefit immensely from their absence.

      As for me; I LOVE what Hack-a-Day provides, and even know how to skip those hacks that I feel don’t offer me anything in the way of advancement/enjoyment. Most of the time I ignore the negativity, but just now HaD is under new management, and I’d hate for them to get the wrong idea(s) just because an outspoken minority with no standards of decency voiced negativity about hacks which, indeed, were appreciated. Most of the people who appreciate them do so without comment, making them a silent majority, easily overlooked by our new evil overlords.

      >> Maybe you should make your own hackaday “elite” site…

      Impossible. That would require time, effort, and resources – and above all the ability to manage those three elements wisely. These negative people’s silly whiny comments AND their lack of ability to navigate their web browser (thus wasting their precious time watching everything that’s fed to them) all illustrate their ultimate lack of ability — if it goes beyond posting negative comments they’re just powerless. We’ll just have to deal with (read: ignore) them for now, until they get bored and slope off to a party (or something), somewhere…

      This place used to be unbelievably positive. Still is, in some ways – just gotta’ avoid/skip/ignore the negative groupthink that seems to have arisen lately.

      And before the next troll posts something stupid like “Well, post something worthy…” or the like, I pre-emptively challenge them to provide something post-worthy. DO something. Complaining is one thing, but what have you contributed? Let us see your hacks – show us your creative resourcefulness! Be part of the solution you seek, or learn restraint with your posts. Because useless flame wars over idiotic ideologies are for congress (which is opposite of progress)…

      [* The last statement alone should provoke some mindlessly entertaining flame wars. Sorry about that - sometimes it simply cannot be helped...]

    • Rob says:

      Troll much LongFist (you too, regveg)? I don’t tolerate videos. I’m not an old fart (the get off my lawn bit was my attempt to inject some humor into my post). I don’t think I’m alone in this. If no one takes the time to request a feature and explain why, then no one knows that a feature is desireable and that having it might engender more appreciation of the site. Having read the summary, I think this was a terriffic hack. Nothing in my “please tag as video only” post was denigrating the hack itself in any way. I just wish there could have been a text component to the project, and as there wasn’t, I wish that HAD had pointed this out so that I wouldn’t have gotten my hopes up. So I made a request.

      I find it ironic that your flame post telling me to “act like you or go away” (my takeaway, not your actual words) is 12x as long as my first post and 6x as long as my follow-up. You must be a special flower.

  6. HomelyPoet says:

    @Hack-a-Day:
    Thank you for rectifying that.

  7. Anon56821293514 says:

    the video vs text thing is because you think only rich people deserve to find out how it was done.

    NOT EVERYONE CAN “GET-TO” A HIGHSPEED LINK TO WATCH YOUR VIDEO !!!

    it takes 20 – 30 minutes on dial-up to cache a 5 minute video
    if the video’s minimum is 480p

    it takes 2 – 3 seconds to load a text page,
    not counting the ad’s or pictures which can be turned completely off

    granted the project involves something almost exclusively sold in volume on ebay,
    its still nice to be able to read articles even if we dont intend to buy it,
    instead of being teased with “for highspeed only”

    its a free to learn webpage but only for people that have money
    dont be “more-equal”

  8. evolotion says:

    Im with the “videos are annoying” crowd, for a project I much prefer to read text so some kind of marker , even a discrete [v] or something would do, but video does have its place, I like watching lecrures, and often have the likes of eevblog on on the background while working on other things. But a hack/project is imho much nicer as a series of forum posts or detailed blog without too much page clicking. Only thing worse than videos is instructables where one must click to a new page as devoid of information as the last.

  9. Forward Declaration: I am the guy that done the hack. For what its worth I think HAD failed a bit here (sorry Brian but thank you for featuring the hack), taking a reporting stance is great, but IMHO the failure here was to reference the video directly instead of the actual blog page that this video is part of. Perhaps I need to make it clearer in the video that there is in fact a supporting “text” page on my “written” blog. The original page is here (also already mentioned in a previous comment).

    http://gerrysweeney.com/build-a-10mhz-rubidium-frequency-standard-and-signal-distribution-amp-for-my-lab/

    Now I will take note of the feedback and will try to put some more written content together in the future, at least enough to try to convince the video haters that it might be worth a watch.

    I am sorry for those that don’t like video, I happen to like to communicate using that medium, I think its possible to portray way more information than text alone – not everyone can communicate well with the written word, or indeed through reading. Comments like “video is for 6 year olds” does seem a little like a six-year olds comment to be honest – there are more grown up ways of saying you don’t much care for video. I appreciate thats personal preference though. As someone quite wise said above, if video is not your thing, please feel free to walk on by.

    Now I will take on board that more supporting text content would be good. I do try but time is limited mostly and as it happened, I done this hack in the afternoon and had a 2AM flight to catch the following morning, so the hack was done, the video editing was done and upload was started. I published the blog article and put it live while sitting in a hotel foyer in Ibiza – point is, it was a bit of a rush.

    Gerry

  10. MS3FGX says:

    I have to agree, if there is no writeup for it, the post should have [VIDEO] (or something similar) in the headline so we can decide if it’s worth looking into or not.

    It’s only logical to make a clear distinction between different categories of content (Howto, Video, Review, etc, etc).

    • Greenaum says:

      Doesn’t really need to go that far. It’s just video-only links that are so annoying (and it’s nice to find out I’m not the only one it bothered the hell out of).

      Either a little, textual ideally, marker for video-only links, or better, just point it out in words in the article description on the front page. I appreciate that the policy already is to prefer to link to write-ups.

  11. evolotion says:

    One of my main issues with video is I browse the internet on my lunch in work, working a hands on job I dont have the luxury of sitting at a desk all day, the fact that I sit on my phone thro lunch is pretty antisocial as it is , im certainly not going to start playing a video while others are trying to talk, so I try check out the videos of interest when I get home.. ill still watch videos of interest but text lends itself to being read (excuse the pun) in more situations.

  12. FractalVoid says:

    Gerry,

    Thanks for the project description. I downloaded the video at 360p (more than 250 MiB) and can’t read the PIC code. Is the code available for download somewhere? Thanks in advance. I’m with the guys that like your technique, good info.

    • This should be close It would be if the code tag worked properly:

      // PIC12F675 Configuration Bit Settings

      // CONFIG
      #pragma config FOSC = INTRCIO //Oscillator Selection bits (internal oscillator: GPIO on GP4/GP5)
      #pragma config WDTE = OFF //Watchdog timer Enable bit (WDT disabled)
      #pragma config PWRTE = OFF //Power-Up Timer Enable bit (PWRT disabled)
      #pragma config MCLRE = OFF //GP3/MCLR pin function select
      #pragma config BOREN = OFF //Brown-out Detect Enable bit
      #pragma config CP = OFF //Code Protection bit
      #pragma config CPD = OFF //Data Code Protection bit

      // Implementation Strategy
      //
      // Pin Assignments
      // 2 = RBS_RDY (GPIO5)
      // 5 = POWER_STATUS_LED
      //
      //

      // We are running the chip at 4MHz
      #define XTAL_FREQ 4000000

      #define RBS_RDY GPIObits.GPIO5
      #define POWER_LED GPIObits. GPIO2

      void main(void)
      {
      ADCON0bits.ADON = 0;
      ANSELbits.AND = 0;
      VBCON = 0;
      CMCON = 0x7;

      //Set up the IO pins
      TRISIObits.TRISIO2 = 0;
      TRISIObits.TRISIO5 = 1;

      while(1)
      {
      if(RBS_RDY == 0)
      {
      POWER_LED = 1;
      }
      else
      {
      if(POWER_LED == 0)
      {
      POWER_LED = 1;
      }
      else
      {
      POWER_LED = 0;
      }
      _delay(400000);
      }
      }
      }

    • I have updated the blog page with some further information. Specifically the PIC source code, the schematic for the PIC in the unit, and for the programmer (ICD3) ICSP connections to program the PIC. I have also uploaded the outline schematic illustration of the video amp I used in the video to describe the transmission line.

      http://gerrysweeney.com/build-a-10mhz-rubidium-frequency-standard-and-signal-distribution-amp-for-my-lab/

      Also, having a closer look at the BNC’s they may well be 75ohm, but in all reality it really does not matter for this application. As someone said above, that bit of the transmission line is like running a car over a pebble.

      I am almost certainly going to do a “short” follow-up video to answer some of the questions that have been asked repeatedly *and* to do something else with the PIC other than run the power LED which seems to have gotten some people all relied up :)

  13. static says:

    Good grief More often than not the first link in a post to Hackaday takes us to the builder /hackers primary web content on a project. Here it take that long to use the link too see that a video is the only documentation. Yea I like to see text & photo project documentation, preferably not in a forum or imgur. but I’ll take what I can get without complaint Hackaday should consider the request to ID video only carefully, once you get started, but forget to do on occasion there will be belly aching. In the event the decision to honor the request up it in a way so that doing a serce for video project doesn’t return article soles based on video only indicator. My self I bookmarked the ~76 minute video to view it if there’s isn’t anything I don’t was too watch. Very unlikely I’ll duplicate the, I just may learn something else.

  14. FractalVoid says:

    Brian and Gerry – thanks for the code and update.

  15. Gerry says:

    I have posted an update on my blog covering some of the questions that were raised. I also fitted the heat sink I received and I have resolve an issue with the 1 PPS output.

    http://gerrysweeney.com/10mhz-rubidium-frequency-standard-and-signal-distribution-amp-follow-up/

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