Intermittent buzzer (CB20494E)

This two-tone buzzer can be powered by a solar panel. The circuit is from a 1991 documentation. The transistor is a general-purpose type.

Four Transistor Reflex Receiver (CB961E)
This an old commercial receiver found in a year 1958 magazine. The circuit uses some transformer...
Input Current Sensor (CB5409E)
This circuit is from 2005 Linear Technology documentation. The circuit applies to 12 V systems and...
Source Follower FET stage (CB4687E)
In the figure we have an amplification stage with FET in the source follower configuration. The circuit is...