Variable RC Oscillator

The "R-C" in this Project's name stands for "resistance-capacitance." We've seen how just varying resistance or capacitance can affect oscillator operation ... this Project lets us see the effects when we change both.

Look at the schematic for this Project, You'll see that the Select Switch chooses between two different capacitors, And you can also see that the switch adds a second resistor to the circuit.

Set the Select Switch to B. Now press the Key. What kind of sound do you hear from the Speaker?

Now set the Select Switch to A and press the Key again. Is there any change in the sound?

Now turn the switch to ON and again press the Key. Try both settings of the Select Switch while the switch  is set to ON and see what happens.

Which combination gives you the highest tone? The lowest?

What does this tell you about how capacitors and resistors affect each other? (You might want to review Projects Resistors and capacitors together ... that's a hint!)