We found this circuit in a French documentation from the 80's. The components used are still common and the circuit can generate signals from 10 Hz to 100 kHz.
This circuit was obtained from an American publication from the 60's. The transistors are...
This circuit detects light variations using two LDRs as sensors. Operational amplifiers and...
Using the 555 this circuit was found in a Popular Electronics from the 90's. The circuit directly...