App note from Renesas about building a guitar pedal overdrive effect using only 2 x AA instead of 9V battery, this app note demonstrate the low rail to rail voltage OpAmp SLG88104V in use. Link here (PDF)
Amplified guitars appeared in the early 1930’s. However, at that time early recording artists strove for clean orchestra type sounds. By the 40’s DeArmond manufactured the world’s first standalone effect. But at that time amplifiers were valve based and bulky. During the 40’s and through to the 50’s even though clean tones were prevalent, competitive individuals and bands frequently turned their amps volume up to overdrive status and the distortion sound became increasingly popular. In the 60’s transistor amplifiers started to be manufactured with the Vox T-60, in 1964 and around the same era to further preserve the distortion sound which was very sought after at that time the first distortion effect was born.