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American Optical Microscope Illuminator: New Bulb!

A classic American Optical microscope illuminator emerged from a box, minus its bulb. Some rummaging turned up a reference for AO bulbs, so I knew I needed a GE 1460 prefocused bulb. Those seem to be a bit rare these days, with 1460X bulbs sharing the same base with a slightly different glass envelope shape. As nearly as I can tell, as long as the filament sits in the same location relative to the base, it’s all good. Five bucks and a few days brought a new 1460X bulb to the bench, a few drops of Caig DeoxIT slicked the holder’s rather gritty contact patches, and the new bulb fit perfectly:

Microscope Illuminator - 1460X bulb - detail

Microscope Illuminator – 1460X bulb – detail

And it lit up just fine, too:

Microscope Illuminator - 1460X bulb - turned on

Microscope Illuminator – 1460X bulb – turned on

That’s running at the lowest of three selectable voltages: 5, 6, and 7.5 VAC, respectively. Given that the bulb spec says 6.5 V (at 2.75 A!), you best have a spare bulb on hand if you need the highest setting. At the nominal 6.5 V, it’s good for 100 hours; 6 V should eke out many more hours.

A generously articulated arm holds the illuminator for desk work:

American Optical Model 651 Microscope Illuminator - on base

American Optical Model 651 Microscope Illuminator – on base

That long snout fits into the pair of holes in the arm of my stereo zoom microscope to cast a bright light directly on the subject. The LED ring light makes that less necessary than before, although sometimes distinct shadows help pick out the details:

Microscope Illuminator Test

Microscope Illuminator Test

That’s the failed WS2812B LED from the Noval tube, which again shows I need a USB camera with better resolution …

The data plate on the bottom of the illuminator, should someone need it:

American Optical Model 651 Microscope Illuminator - data plate

American Optical Model 651 Microscope Illuminator – data plate

The optics cast an image of that white-hot filament out into space, so I think the diffuse active area of a white LED wouldn’t produce the same amount of light on the target. I have some Pirhana LEDs, though, so (when this bulb fails) I’ll see about that.

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