Found in a 90s Popular Electronics, this circuit uses a 741 to generate frequencies from 0.1 to 30 Hz. Observe the phototransistor feedback.
March 2017 - Texas Instruments LM5166 Synchronized Buck Converters are available at Mouser for 3V...
This circuit is from 70's documentation. The converter used is not a common component today. |...
It can be obtained from Mouser Electronics new crystals for surface mounting from AVX with...