Found in American documentation from the 1980s, this circuit makes use of components of the time, which are uncommon today. The circuit detects the approach using a sensor formed by metal plates.
This two-channel DC volume control uses a transconductance operational amplifier. The transistors can be...
The CMOS 4046 integrated circuit is not very common today, consisting of a very efficient PLL for...
This is the project we have described, as found in a 1981 documentation. In the figure we show the...