The purpose of this circuit is only to increase the input resistance of a multimeter, since there is no voltage gain. The batteries are 9 V and operational equivalents can be used.
Found in American documentation this circuit uses transistors of the time. The circuit can be made...
The TAA300 integrated circuit is not common today. In fact, the circuit shown is from a Dutch...
This circuit was found in a 1980s documentation. Q1 and Q2 can be BC548 and SCR a TIC106. The...