Go Down

Topic: Variable resistor (pot) - Even results? (Read 1 time) previous topic - next topic


I'm building a toy for my little boy with a bunch a blinky lights, buttons and plugs.
I'd like to put a Pot on so that it will make a clicking sound when he turns it or change the flashing rate of an LED.

The 500k variable resistor is connected fine and I can Serial.print it's values correctly. The values are logarithmic (i think). Can anyone suggest a way to convert the values so that when the knob is turned the clicking or flashing speed has more of a x=y ratio? 


Sounds like you have a pot with an "audio taper". A simple way to correct (without fancy math) is to characterize the pot. Set it to the 0-degree setting (all the way counterclockwise), take a reading, store it in a spreadsheet. Turn the pot to 10 degrees, take a reading, store it in the spreadsheet. Continue all the way around.

Now, turn this spreadsheet around. Store it in an array in your code, then whenever you get a reading, look it up in the table (you'll have to look between two nearest values) and the index into the table is the linearized return value.

The Gadget Shield: accelerometer, RGB LED, IR transmit/receive, speaker, microphone, light sensor, potentiometer, pushbuttons


I see three options

1) Use a lookup table as RC suggests
2) Go out and buy a linear pot
3) Describe logarithmic principles to your lad, this has the added beneficial side affect of giving him a head start in maths :)

Rob Gray aka the GRAYnomad www.robgray.com


Ha thanks guys. Right now we are working on the Principals of Electrical Theory. I'll going to give the 'array' idea a try. Thanks.


Go Up

Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

via Egeo 16
Torino, 10131