Two-tone solar buzzer (CB20493E)

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

Phase shift oscillator (CB21668E)
This phase shift oscillator generates sinusoidal signals in the audio range. Frequency depends on...
Fast Symmetric Zener (CB12086E)
We obtained this circuit in an English publication in 1983. Equivalent operational amplifiers can...
Inverting amplifier LM741 (CB25917E)
The figure shows how to implement an amplifier with gain 10 using the operational amplifier LM41....