Light beam switch (CB21413E)

This circuit was obtained from a 1965 General Electric SCR manual. The components are from the period.

Darlington touch switch (CB9564E)
Any high-gain Darlington transistor can be used on this touch circuit. The load can be formed by...
Current Sensor and Fuse Monitor (CB5222E)
This circuit is from a 2005 Linear Technology LT6100 Application Note. The circuit provides a...
Voltage Follower MC1439 (CB19673E)
The operational used is like the 741 and the voltage gain is unitary. The circuit is from the...