Help with Spiro

I've almost finished my spiro but I'm having problems varying the speed of them using 100k pots, I had a good look and saw I need a PWM. Do I need a seperate PWM for each pot or could I run all 3 pots from the same PWM ?

The motors are mini 3V similar to whats here 2pcs DC 3V 6V 130 Motor 2000 RPM for DIY | eBay

that seems like a high value for the pots. I've used 25ohm with success.

Michael.

Yeah I use 100 ohm rheostats from radi0shak