The circuit below was suggested by the Motorola Linear Databook of 1990. The component used is uncommon and the power can be between 7.5 and 12 V.
This circuit from the 40's is a conventional analog multimeter with several scales. Its accuracy will...
This preamp with several inputs using germanium transistors from the time was found in Japanese...
We found this configuration in a 1975 publication. It can be implemented easily, as it uses only...