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 is a two-input audio switching circuit. The operational can be of any type and more entries can...
We found this amplifier for automotive use in the Philips integrated circuit manual from 1990. The...
Found in old English documentation this circuit can be made with a BF245 or equivalent. Coils are...