We found this circuit in an American documentation from the 1990s. The circuit is based on the LM3909, a low power oscillator from National Semiconductor.
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...