Analogue volume control

Hi there,
this is my first post, and quite noob, please be gentle.

I would like to be able to control a regular potenciometer thorough Arduino.
The thingy is that I would like to adjust the volume pot of the old arcade cabinet in a time schedule, for day and night different profiles, louder in the night actually.
Is stupid idea? Doable?
Thanks in advance.

If you want to adjust the volume without messing with the electronics of the old cabinet then you are going to have to make some kind of physical connection to the knob or spindle of the pot.

The first thing to find out is how many turns the existing knob makes.
If you want to make one turn or less then a servo would be the best choice.
For more than one turn you could use a stepper motor or a servo with some gearing or a DC motor with lots of gearing.
In all cases a belt beween the motor and the spindle of the knob might be the be the least intrusive form of connection.


I would like to be able to control a regular potenciometer thorough Arduino.

That's not really clear... If you want to actually rotate the pot of course you'll need a motor.

Or, there are [u]digital pots[/u]. But it can be "iffy" replacing a regular pot in an unknown circuit. You have to be careful about the voltage and current, including the negative-voltage swing of an audio signal.

Or, you could use a relay to switch-in a (2 resistors) when you want it quieter. (You could leave-in the pot). In audio terminology, a voltage divider is called a "pad", and pot is a variable voltage divider. With the relay and voltage divider, you'd have a normal-range and a quiet range.

The day/night could be tricky too... There is a "timer" built-into the Ardino (so you could turn it on/off every 12 hours) but it will drift and you have to figure-out how to initialize/set it the first time. If you want better day/night control, you'll need to add a real-time module.

...After a little more thought - I'd go with the voltage divider (or a 2nd pot) and a relay. And, I'd just use a toggle/reset button to switch back-and-forth and reset the timer. So, you could hit the button in the morning or evening to start the timer and then re-start whenever it drifts too-far off. (The "day" and "night" times don't have to be 12-hours each, they just have to add-up to 24-hours)

You wouldn't need any kind of display and the only "user interface" would be one button.

You'd have to convert hours to milliseconds.

You'll need a relay board, or a relay driver circuit because the Arduino can't directly-drive a relay.

For stereo, you'd need 2 voltage dividers (or two additional pots, or another stereo pot) and a DPDT relay.

And for development purposes you'd want to start with the timer set to one minute or less so you don't have to wait 24-hours to find-out if it's working. :wink:

Remember that volume control is logarithmic, so that a pot replacement should be logarithmic as well.

Attaching wires to the volume control is critical, very susceptible to catching electric noise.