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Project Notes

#081 DoubleShiftWithFETs

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

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 7-SegmentCMOS/TTLArduino
Project Source on GitHub Return to the LEAP Catalog

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!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.