The circuit shown has a voltage gain of 500 times and can use equivalent FETs like the BF245. The circuit is suggested by National Semiconductor in its 1994 Linear Applications Handbook.
The circuit shown in the figure is the version activated at the low level, of the previous circuit...
This circuit is from an old American documentation using LEDs in the rectification. The circuit...
This circuit consists of an emitter follower, presenting unit voltage gain implemented with an...