First guitar effect (Trem Trol 800 Tremolo)In 1946 the DeArmond company in Toledo, Ohio releases the first ever standalone guitar effects unit (Trem Trol 800 Tremolo). It's not a pedal but it is a box that you put on top of the amp and it gives you tremolo. The way it worked was passing the guitar signal through a water-based electrolytic fluid to augment the original tone.
Electronic drumsThe first electronic drum kit was created in the early 70s by a drummer called Graham Edge who was the drummer for the band "The Moody Blues". The design included rubber pads with silver backing that used a magnet on a cord moving up and down to trigger an electronic signal that would then be processed through transistors.
You can hear Graham Edge’s electronic drum kit in action on the Moody Blues song “Procession” from “Every Good Boy Deserves Favour”:
Electronic drum kit (Simmons SDS-V)In 1978 Simmons created the Simmons SDS-V, a fully electronic drum kit, complete with its signature hexagon pads and 5 modules (bass, snare and 3 toms). This was the first electronic kit of its kind to be commercially available. It's one of the highlights of the 80s when it comes to electronic drums, as a lot bands used these type of drum kits in their live performances and music videos.