Found in a 1980s documentation, this circuit uses as base a component of the era. The formula for determining the conversion is given next to the diagram.
This circuit is from a 1988 publication. It makes use of an LM3914 LED driver circuit, still...
This configuration based on a conventional astable multivibrator was found in a 1982 publication. The...
Found in Philips documentation from the 1970s, this circuit uses components from the era. The...