This circuit of a 1964 Electronic Design uses a photodiode from the time. Modern equivalent can be used. The standby current is 1.2 mA.
With this circuit it is possible to divide the frequency of a rectangular signal by values between 2...
This circuit, which we find in a documentation from the 70s, filters out the Ru [occurring in...
This circuit simulates the call tone of a telephone. The transducer is a high impedance capsule, and...