This amplifier for instrumentation with very high input impedance was found in a manual of JFET circuits. The operational ones used are current and the power supply must be symmetrical.
This circuit was found in a Mullard transistor manual from 1960. Note the symmetrical power...
This amplifier step with a transistor has an input impedance of 100k to 10 M. The transistor can be any...
I found this little signaling transmitter in old American documentation. The circuit has a good...