This circuit is from a 1972 Motorola publication. The used transistor can still be found, but it can be used equivalent. The circuit is powered by the amplifier with which it must operate.
This circuit was found in Linear Circuits Applications of Texas Instruments, originally using the...
This configuration makes use of currently uncommon components. In fact, we found it in...
This 1969 Mullar circuit appears elsewhere on this site. The circuit uses germanium diodes and the...