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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

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 just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - 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
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.