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Project Notes

#183 PolarityTester

demonstrate a polarity-testing circuit


A simple polarity testing circuit uses a series of inverters. The input signal is pumped into two parallel chains:

  • a single inverter
  • a series of two inverters

So, regardless of input polarity, one chain output will be high and the other low.

input Single-inverter Output Dual-inverter Output

The signals are tied together with two reverse-polarity LEDs in series. So one will always be alight when the other is not. The unlit LED is subject to a reverse voltage equivalent to the forward voltage of the other LED. Most LEDs will handle this without complaint.



The Schematic

The Build

Credits and References

About LEAP#183 InverterCMOS
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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is my personal collection of electronics projects, usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting (IMHO!).

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