The 1970s was a great time to be an electronics hobbyist, as a whole new world of analogue integrated circuits was coming down in price while new devices would appear to tempt the would-be constructor. Magazines and project books were full of simple circuits to do all manner of fun things, including many synthesizers and sound generators.
We’re reminded of those days by [Burkhard Kainka]’s triggered sound generator, which couples an op-amp timer to another op-amp phase shift oscillator to produce a sound described as “the unwilling meowing of a cat, which does not want to be disturbed“. Yes, we did make things like this back in the day.
The timer is triggered by a few millivolts on its input, which can come from a bit of mains hum or a flash of light to an LED operating as a photodiode. This provides enough DC voltage to the input of the phase shift oscillator to start oscillation, and in turn the oscillator drives a piezo speaker. It’s a fun little project, it shows that a microcontroller isn’t always needed to make something work, and maybe those of you without the experience of a 1970s childhood can learn a little bit of analogue magic from it. Need to know op-amps better? Read our primer!
7 thoughts on “Op Amp Contest: A Slice Of The ’70s”
Ramzi Yousef Casio watch op amp implementation eclipses all other op amp projects?
Why did high tech hater mathematician Ted Kaczynski not implement op amp fusing?
Too much math?
Not enough practical electronics? :)
Pretty cool and simple project. Also nice seeing people use ‘disposable’ vape batteries in projects.
Yes I noticed that too. I have a fair collection of them now.
Another great project that Burkhard Kainka did.
There are loads of brilliant ideas on his website
And many analog Kits – some of the booklets I translated for the non-German community,
especially the one where you “program” the functionality using jumpers
– like a very simple “Analog Array.”
and the English book you find here:
It was really fun to work through the examples
And regarding more of the analog stuff on Burkhard’s website see for example
The descriptions are in German, but I just did a quick translation for the non-Germans
You find it there as well
I was always impressed with the “Hassler” Robert Pease designed back in the 1990s. The man was an analog artist of first order.
Please be kind and respectful to help make the comments section excellent. (Comment Policy)