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Project Notes

#081 4x7-Segment Double Shift With FETs

Driving a 4-Digit 7-Segment LED display with only 3 pins, using two 74HC595 shift registers and some n-channel FETs

The Build

Notes

This circuit is a variation of the DoubleShift experiment that demonstrated how to use two 74HC595 shift registers and some NPN BJTs to drive a 4-digit 7-segment display with only 3 Arduino GPIO pins.

The only difference here is that the S9013 NPN BJTs are replaced with 2N7000 n-channel FETs.

When fully on (e.g. displaying 8888), it appears the display and associated components on the breadboard are drawing an average of about 2.47mA (compared to 2.87mA with BJTs).

Construction

The Breadboard

The Schematic

The Build

Credits and References

About LEAP#81 LED7-SegmentCMOS/TTLArduino
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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of 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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