We found this circuit in an Australian publication from 1991. It is a kit of the time with input for a guitar pickup. The range is a few tens of meters.
This low drift or offset circuit is from an 80's documentation. The configuration can be made with...
This is a commercial circuit from a Japanese publication from 1972. The circuit uses a FET that...
This instrumentation amplifier was obtained from Popular Electronics in 1993. The operational...