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Project Notes

#564 USB Blinky Toy

A curiously hypnotic USB blinky demonstration of a variable frequency/variable duty 555 timer circuit.


Here’s a quick demo..



This is a quick demonstrator for the LEAP#563 Dual Variable Mode Oscillator just for fun.

I’m using the shell of an old USB Webmail Notifier device for mounting the circuit.

It is curiously hypnotic to play with:

  • switch between variable frequency/fixed duty and variable duty/fixed frequency mode
  • use the variable resistor to adjust the frequencvy or duty (depending on mode)

Four strawhat blue LEDs provide enough illumination for the shell, with fairly low current limiting resistors (100Ω). The 2N7000 has just enough current handling capability (200mA continuous) for the 4 LEDs.


the circuit extends the Dual Variable Mode Oscillator circuit with a N-channel FET low-side controlled array of 4 LEDs.



Putting it in the shell

I opted for a freeform construction of the circuit rather than squeeze a PCB into the box. Only the power lines of the USB connector are used.



Credits and References

About LEAP#564 555 TimerOscillatorsLED
Project Source on GitHub Project Gallery 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.