Q.Reed Ghazala coined the term in the 90's but discovered the idea in the late 60's when a small transistor radio short circuited in his junk drawer and made synthesizer type sounds.
Truly any electronic devices from a pocket calculator to AC motor can be circuit bent to make sounds but th emost popular targets are children's toys like the infamous Texas Instruments Speak & Spell as seen in ET or the low budget Casio SK-1 sampling keyboard.
When used as a verb, it often means the opposite of circuit bending, i.e. to denote success in repairing something technical. 'When my car smoked, I had to circuit bend the motherfucker to get it running again, fuckin stayed up all night doin' it too.'
A: "Naw, don't think so, but I heard they had a broken Super Reverb."
2. While circuit-bending, he burned the silicon chip with his soldering iron by accident.
3. Her circuit-bent speak and spell made incredibly intricate noises; everyone was surprised, however, that she used only cannibalized audio cable and tape.