The use of field effect transistors in this circuit improves its performance. This configuration is from a 1975 circuit manual. The transistor can be any general-purpose FET such as MPF102 or BF245.
We found this configuration in a documentation for radio amateurs from 1974. The circuit can be...
Texas Instruments' low power operational amplifiers OPAx196 can be found on Mouser Electronics....
This low power amplifier circuit for speaker or phone is from the Philips Databook of 1990. The...