Category Archives: comparator

A Daylight-Readable Bar Graph Display in the 70s Wasn’t Cheap

LEDs weren’t always an easy solution to displays and indicators. The fine folks at [Industrial Alchemy] shared pictures of a device that shows what kind of effort and cost went into making a high brightness bar graph display in the 70s, back when LEDs were both expensive and not particularly bright. There are no strange materials or methods involved in making the display daylight-readable, but it’s a peek at how solving problems we take for granted today sometimes took a lot of expense and effort.

The display is a row of 28 small incandescent bulbs, mounted in a PCB and …read more

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Posted in 70s, bar graph, comparator, daylight readable, display, hardware, incandescent, led, machined aluminum, minitron, retro, retrocomputing, wamco | Leave a comment

Custom Circuit Makes for Better Battery Level Display

Isn’t it always the way? There’s a circuit right out of the textbooks, or even a chip designed to do exactly what you want — almost exactly. It’s 80% perfect for your application, and rather than accept that 20%, you decide to start from scratch and design your own solution.

That’s the position [Great Scott!] found himself in with this custom LED battery level indicator. As the video below unfolds we learn that he didn’t start exactly from scratch, though. His first pass was the entirely sensible use of the LM3914 10-LED bar graph driver chip, a device that’s been …read more

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Posted in bargraph, battery, battery gauge, battery meter, comparator, led hacks, lm324, lm3914, misc hacks, voltage | Leave a comment