Microgram electrobalance

scale

As with most precision equipment, microgram scales are usually very expensive. The close tolerance machining of sapphire pivots and computer control add to the cost. Not all of those components are necessary though. This article from Scientific American demonstrates how to build a simple microgram balance using a salvaged galvanometer. Once calibrated, the output voltage will have a direct linear relationship to the weight. There is a more recent version of this project that uses a microcontroller to overcome static friction and auto center.

Comments

  1. ... says:

    wow, a microgram balance. That hack came out about 5 years ago… But in any case, they can be made quite a bit simpler, see http://www.sci-spot.com/Mechanical/balance.htm for an even simpler design; with a digital readout!

  2. ADam Shaver says:

    If you were to take into factor the first and second order frequency repsonse of the newer device to perturbation (such as a sinusoid changing the voltage on the galvanometer) and then use peturbations to weight the sample, you could probably increase the mass resolution by an order of magnitude or more. See http://www.physorg.com/news3533.html for what I’m talking about. Its kind of like a taylor/fourier expansion when weighing things. The DC or constant terms can be used, but more data can be gathered from considering perturbations (higher terms).

  3. weaszel says:

    perturbation? my mom caught me doing that once and took my computer away for a week.

  4. a wee question: what would one use one of these for? I see that it’s really neat, but for what sort of practical use might this be deployable?

  5. ryan says:

    cocaine distribution.

  6. >>Posted Sep 28, 2005, 12:14 AM ET by ryan
    >>cocaine distribution.

    Correction: Exceedingly accurate small-quantity cocaine distribution

  7. idlemachine says:

    Exactly. It’s so those damn cheapass bitches who waste your time hitting you up for a lousy point don’t get a single goddamn microgram they haven’t paid for.

    This ain’t no charity…

  8. Kiamors says:

    I would probably say, if it was going to be used in some kind of drug manufacture and distribution, it would probably be LSD. its the only substance where micrograms really matter.

  9. Martha Focker says:

    and fentanyl / other high potency opiods

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