This circuit was found in Texas Instruments documentation from 1968. The transistors are from that time, admitting modern equivalents. The response ranges is from 20 to 20 000 Hz.
This field strength meter for the 11-meter range was found in Radio Electronics magazine from...
This circuit is from a 1980s Signetics documentation. Equivalent operational amplifiers may be...
This circuit was found in an old manual of integrated circuits. The operational is of the time,...