We found this circuit in a 1977 documentation. The National Semiconductor's LM380 is no longer easily found, but if used on this amplifier it provides excellent reproduction quality.
This sophisticated circuit with two LF411 operational amplifiers appeared in the November 1984...
This circuit uses battery power, but it can be powered by an 80 to 200 V power supply, with no...
This interesting circuit, which can be used as an alarm, was found in a 1997 documentation. It...