This circuit was suggested by Sprague Electric in an 80's documentation. The circuit uses a tachometric sensor for feedback. The current was not indicated in the original documentation.
The LM1468L can also be used. The circuit is from Motorola's Linear Interface ICs and the...
We found this light-effect circuit with LEDs using the well-known 4017 in a 1987 documentation. All...
This circuit was found at Popular Electronics. The speaker is of the greater than 100-ohm...