This circuit was found in an English publication from the 70s, an article that teaches how to calculate instruments. The circuit is still current and can be built with an analog indicator of 100 uA.
The filter shown in the figure can have its cutoff frequency adjusted between 2 kHz and...
This circuit, which uses a quadruple comparator, was found in old American documentation. The...
This shield for controlling the direction of rotation of DC motors up to 500 mA with BD135 / 6 and...