>"One random variation I tried, was to use LEDs in series with the base of the transistor. In combination with PMBT3904 transistors, this surprisingly yielded

>"One random variation I tried, was to use LEDs in series with the base of the transistor. In combination with PMBT3904 transistors, this surprisingly yielded an oscillator that switched between frequencies that were several orders of magnitude apart when varying the supply voltage. A closer look revealed a region with unpredictable behavior close to the switching voltage." Fascinating!