This is a typical point scale or moving bar circuit with the LM3915. We found it in old American documentation. The operational amplifier supports an equivalent modern type.
We found this circuit in an American publication in 1975. The circuit generates an adjustable...
This simple 1-transistor audio preamplifier appeared in the June 1968 Radio Electronics magazine. The...
This circuit is from a 2004 documentation serving for signals from 1 MHz to 160 MHz. The antenna is...