PWM pot to A0-----little help

Other Hardware General Electronics
1

Hi

I have been using pin 9 for PWM and require at least a range of 4 octaves .

I'm using a linear 100k pot to analog pin A0 to vary the frequency.

The ADC is 10 bit and has a resolution of 1024.

the results are as follows.

110hz = 0volts

220hz = 0.625volts

440hz = 1.25volts

880hz = 2.5volts

1760hz = 5volts.

That's as expected .

This is exponential and causes very small changes in the second half of the pots travel.

In short a PITA when trying to tune a lower frequency.

This is more like hertz/volt.

Is there some way i can make the ADC deliver a 1volt/octave response?

Thanks for listening.

2

Using a logarithmic pot will get you a lot closer.

Steve

3

If you want linear response from 110 to 1760, try (Volts * 330) + 110.

4

slipstick:
Using a logarithmic pot will get you a lot closer.

Steve

Thanks for the reply

I had tried a log pot earlier , but it only made it worse----really tight at the bottom end.

best regards

5

JCA34F:
If you want linear response from 110 to 1760, try (Volts * 330) + 110.

Thanks for the reply JCA34F.

This is the code used for frequency.

float frequency = 110 + (analogRead(A0) * 1650.0) / 1024.0;

Where should i put your suggestion?

Best regards