2EI4O

Logic level test pen

Overview

When debugging the serial port, a multimeter simply couldn't detect voltage changes of more than a few bytes, so a level tester was made.
This solves the problem of multimeters not easily measuring high and low levels, providing a visual display of these levels. The image below is of the older version; the newer version hasn't been prototyped yet.

Advantages of this solution:
1. No switch required, ready to use.
2. Simple circuit, suitable for DIY .
3. Convenient charging; simply plug it into the USB port of the charger (USB charging added in version 1.1).

Measures high and

low levels.

Design Files

BOM_Logic Level Tester.xlsx

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It is your responsibility to test the circuit yourself and determine its suitability for you. EEWorld will not be liable for direct, indirect, special, incidental, consequential or punitive damages arising from any cause or anything connected to any reference design used.

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Update:2026-03-28 07:36:53

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