This circuit was obtained from an 80's EDN. The components used are still common. The circuit can be used as a shield and the frequency is approximately 775 Hz.
In the figure we have the circuit of a multi-range ammeter using a 50 uA full-scale instrument. The...
We found this circuit in a Radio Electronics magazine from December 1969. The circuit uses a...
This blocking oscillator was found in a publication from the 50's. The coils determine the...