This amplifier, from Philips Databook is suitable for automotive applications. The input resistance is 60k ohms and the frequency range is 20 to 20 kHz.
The integrated circuit used in this configuration for noise reduction on FM radios is not common...
In the figure we have the circuit of a simple voltmeter with a 50 uA instrument and a 2k coil. The...
With this name, we found this electronic stethoscope with a coal microphone in a 1957 Raytheon...