This Linear Technology circuit can measure currents from 100 pA to 100 uA. The circuit is from the 80's, using a component of the era. Transistors are general purpose types.
The CMOS 4046 integrated circuit is not very common today, consisting of a very efficient PLL for...
In the circuit shown in the figure to the side, the relay is activated when the light stops...
With this name, the English publication where we found this circuit indicated a sensitive touch...