Friday, December 15, 2017

A Little Confection

While I'm working on a few projects, I thought it would be good to get something done. So I did. A little logic level tester. This one is a little different. It tests for voltages. Less than 0.5 volts. More than 2.0 volts. And more than 4.0 volts. And yes there is a light for each. Good for looking at mixed voltage logic. And there is also a light for greater than 0.5 volts but less than 2.0 volts. So you get a light for ambiguous (in some situations) voltages. The schematic looks like this:

Click on the image for a larger view.


The circuit will run on 3.0 volts (nominal) but the lights will be a little dim. The voltage response will be the same as it is on 5.0 volt power. The magic of voltage references and comparators.

The complete package including schematics, parts layout, and parts list (in pdf) can be found here.

Engineering is the art of making what you want from what you can get at a profit.

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