Tag: X-ray

  • What’s up, Doc?

    Let me introduce [Howard]. He loves electronics, has a bunch of old scopes, is obsessed with time accuracy, and happens to be a retired medical doctor.

    What do you give a chap like Howard for his birthday?

    Well, his loving son [Nick] had the answer! He gave his dad the ultimate gift – an Oscilloclock Exo 3KP1 with a custom medical-themed animation!

    Hong Kong connection

    [Nick] first reached out in February to check out his options. He explained that the family was spread across continents, but would be uniting in Hong Kong for the big birthday event, in June. Four months away!

    Could Oscilloclock deliver something glorious and mesmerising for his dad – but in time, and within budget constraints?

    Yes and yes!

    The lab just happened to have a set of fully assembled, older-revision boards just begging for love and attention. And also in stock was a beautiful new cast acrylic Exo case and CRT ring set — with some slight imperfections.

    By using these components, we could reduce the time needed to craft the device — and offer a substantial discount to boot!

    The clock was ready and shipped a week ahead of time – making sure [Howard] would not go disappointed on his big day.

    Perfectly Imperfect

    Frequent readers may recognise that your humble Oscilloclock senior engineer has perfectionist tendencies. Any “slight imperfections” come with some concessions.

    On the other hand, owners rarely perceive such imperfections as such. They either don’t notice them, or they actively enjoy them as features, making their beloved device just that much more unique.

    Quiz time! Can YOU spot any blemishes?

    Make a wish!

    [Howard] no doubt got quite a surprise when he turned on his birthday present and saw it literally light up the room!

    No, this was not a pyrotechnic effect made specifically for the occasion! It’s called an inrush current limiter, designed to preserve the longevity of the CRT.

    Howard’s device employs what we call “a sacrificial lamb”. In this scheme, a light bulb is used to absorb most of the switch-on current that would otherwise flow directly into the CRT heater. The bulb lights up brilliantly for a time, then dies out as heater resistance increases and current decreases.

    Primitive. Low-cost. Yet immensely effective. Brilliant!

    Medicine for the Medic

    The Oscilloclock Exo is a popular model. But every clock simply must be unique! [Nick] had just the trick in mind, with a request to incorporate the words “What’s Up, Doc?” to reflect his father’s illustrious medical career.

    Can do. But we took it a small step further — a simple animation depicting a patient standing behind an X-ray exposure screen!

    Eye candy. Proudly minimalist animation on proudly minimalist hardware!

    Post-ceremony

    Private birthday celebrations are private; we have no photos to share here of the ecstasy we hope [Howard] felt when, surrounded by [Nick] and his loving family, he unwrapped his birthday gift.

    However we do have a photo of the clock in-situ, after the trip back home:

    We wish [Howard] many future returns and thank [Nick] for the opportunity to bring joy to the family on their special occasion!


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  • Some time ago, [javadesigner] asked something that no doubt many of you have been wondering: Do Oscilloclocks emit radiation?

    Had a question about oscilloscopes – specifically cathode-ray tubes (CRTs). X-rays etc were discovered in similar tubes, and I’ve read that high kV tubes produce both beta and X-ray radiation.

    … Have you ever measured x-ray emissivity with CRTs, and if so, are there any mitigation strategies – especially for X-rays? Leaded glass enclosures, etc.?

    Great question!

    Will your faithful Oscilloclock do this to you?
    CRT used in this demo: 130BFB31

    Fortunately the answer is a clear NO. Our hand-crafted Oscilloclocks do not emit dangerous radiation.

    The general rule of thumb with CRTs (in fact, any electrical equipment operated in a vacuum) is that X-ray emission is negligible at anode voltages less than around 10kV. The accelerated electron beam simple does not have enough energy to generate X-rays when striking the phosphor screen.

    But above 10kV, X-rays can and are produced as a result of the higher-energy bombardment. The high-voltage CRTs used in television and computer monitors of the day always incorporated lead glass (strontium-barium glass), to block these X-rays. (And… to protect against implosion!)

    In any case, all Oscilloclocks operate at voltages well below 10kV, so this does not become an issue.

    A few of the CRTs in stock - 6498, D4P, 3WP1, 50SB1, CV2302. None emit X-rays!
    Just a few of our CRTs in stock – and none of them emit X-rays!

    Thats right – whether we craft your custom timepiece from a behemoth 6498 (at left, operating at 6 kilovolts), a delightful D4P (3kV), a sleek 3WP1 (1.5kV), a cute 50SB1 (1kV) or an eentsy-weentsy CV2302 (500V), you’ll be illuminated but never irradiated.


    Fascinated by electron beams and phosphor bombardment? Do you have a question that everyone else wants to ask? Query away, we love Q&A!