Two-tone solar buzzer (CB20493E)

This circuit was found in a 1991 publication. The transistor can be a general-purpose type.

Bistable 555 and 4013 (CB15775E)
With each clock of the 555 (negative transition) the 4013 (flip-flop) changes state by activating the...
Two Terminal Current Regulator (CB5280E)
This regulator was found in a 2005 Linear Technology component manual. It is based on the LT1635...
PWM Control (CB1549E )
PWM is the abbreviation for Pulse Width Modulation. What is done in this circuit is to apply...