Found in American documentation from the 1980s, this circuit has a throughput of 700 Hz and a flat response of 400 to 500 Hz, with crystals of 3 MHz. Crystals of 2 to 15 MHz can be used.
In this circuit, the current capacity doubles, but is still of the order of microamps. The...
Although not using transformers, this amplifier may have difficulty mounting if the original...
This interesting benchtop circuit was found in the May 1977 issue of Radio Electronics magazine. The...