Doctor Q

Envelope filter
The legendary effect of the old Electro Harmonix Q-tron is now generally known as Auto-Wah and had its gory days during the 70's, but even today you can still hear this very noticeable sound. The Nano Doctor Q comes in small package and, like his father, is very suitable for making a funky rhythm guitar even more eye-catching and groovy. With the range knob, you have different sound variants available; With the bass switch, the effect can be directed into lower regions - Doc Q will be a wonderful ear catcher for the bass solo as well!

https://www.amazon.com/Electro-Harmonix-Nano-Envelope-Follower-Pedal/dp/B000PHLYNA