Found in a 90s Popular Electronics, this circuit uses a 741 to generate frequencies from 0.1 to 30 Hz. Observe the phototransistor feedback.
This circuit is from an Argentine publication from 1973. It provides a signal to an amplifier from...
This filter was obtained from the Texas Instruments Linear Circuits Applications. It makes use of...
We found this circuit in a 1997 documentation. It can be used in any common 12 V source and has...