The Seemingly Impossible Oscillator

A deep dive into the reverse avalanche oscillator — a circuit using a backwards-connected 2N2222 transistor, a capacitor, a resistor, and an LED, with nothing connected to the base, yet the LED flashes. The behavior is explained through avalanche breakdown: as voltage across the capacitor rises, the reverse-biased emitter-base junction eventually breaks down, discharging the capacitor in a relaxation oscillator cycle. The post explains why a transistor exhibits this behavior (due to a 'hump' in its I/V curve) while a simple diode does not, and why the emitter-base junction has a lower breakdown voltage than the collector-base junction.

Nguồn: https://hackaday.com/2026/07/14/the-seemingly-impossible-oscillator. 8sync News chỉ tóm tắt và dẫn link; bản quyền nội dung thuộc tác giả và nguồn gốc.