Found in a Popular Electronics from the 90s, this amplifier uses an integrated circuit from the time. The circuit operates from the LF band up to 600 MHz with a gain of 16 dB.
This circuit uses common components activating a control relay for the water pumps. The sensors are...
This circuit is from a publication from the 70s. The operational amplifier is from the period. Modern...
The LM121 integrated circuit is no longer common in our market, with more modern equivalent...