The low-noise amplifier shown uses a rare Raytheon operational amplifier today. The circuit can be implemented with more modern operators and the power source must be symmetrical.
In fact, we can say that this circuit found in documentation from the 90s, consists of an intercom...
The basic integrated circuits of this 1988 multimeter are no longer very common today, but if...
This circuit is from an old publication of the 70's. It can be implemented with modern transistors like the...