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Project Notes

#359 HS088 Audio Effects Chip

Figuring out the HS-088 “Ding Dong” audio effects chip.


Here’s a quick demo…



The HS-088 chip produces a typical electronic doorbell “ding-dong”, which repeats three times when triggered. It is very similar to - and not any more pleasant! - than the kind of effect you can get with common 555 circuits like LEAP#059 TwoToneDoorbell.



The chip requires a few external components:

  • 3-4.5 V power supply
  • a small signal NPN transistor such as the S8050
  • 8Ω speaker
  • switch
  • a 100nF capacitor (104)
  • a pull-down-resistor e.g. 10kΩ

A few things to note:

  • most schematics available around the web do not include the pull-down resistor. I found that without this, the effect could be triggered only once and would not reset.
  • the output volume is very low. It seems it would need additional amplification to be useful



Credits and References

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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. 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.