Flood alarm (CB7994E)

This circuit is from a 90s Popular Electronics. The transistors are of general use and the buzzer is a Sonalert type.

Instrumentation Amplifier (CB18979E)
This amplifier with very high input impedance was suggested by Texas Instruments in a manual of...
Stepper Motor Control UCN5804 (CB15680E)
Using only a ULN5804 integrated circuit, stepper motors up to 500 mA can be controlled from TTL...
Constant Current Source (CB13073E)
Constant current sources are used in applications such as battery chargers, electrolytic tanks, etc....