In a lot of circuits (especially with the 555 timer), I see capacitors used to set the duration/frequency of something.
Now mostly the value of a capacitor can be calculated, however, what if I want it to be variable, and controllable from a microcontroller.
I know there exists varcaps/var. diodes etc, but if I look at the data sheets they only mention they are for radio/TV tuning. For resistors there exist variable resistors ICs, and I would expect something similar for variable capacitor ICs.
Do I miss/oversee something here?
See link Example circuit
Using for C: 100 nF Using for R1 and R2: MCP42010 (100 kOhm version, see Datasheet
Slight problem is that the wiper resistance is 125 ohm, resulting in a minimum frequency (using the calculations in the circuit link) when using 100 kohm is 48 Hz, and maximum frequency (when using 125 ohm) is 48 Hz.