Roff
Well-Known Member
How it works
Assume that initially, both capacitors are discharged (zero volts across them). Both transistors will be off. As the capacitors charge through their respective series resistors, the base-emitter junctions and the diode will eventually become forward-biased. Collector currents will cause the collector voltage of Q1 to drop, and the collector voltage of Q2 to rise. Each of these couples to the base of the other transistor through a capacitor, causing the transistors to turn on even harder (positive feedback). Both transistors saturate, discharging the capacitors rapidly. Transistor current gain is too low in saturation for this state to be sustained, so the transistors begin to turn off. Again, positive feedback causes them to snap off rapidly, and the cycle starts over.
Assume that initially, both capacitors are discharged (zero volts across them). Both transistors will be off. As the capacitors charge through their respective series resistors, the base-emitter junctions and the diode will eventually become forward-biased. Collector currents will cause the collector voltage of Q1 to drop, and the collector voltage of Q2 to rise. Each of these couples to the base of the other transistor through a capacitor, causing the transistors to turn on even harder (positive feedback). Both transistors saturate, discharging the capacitors rapidly. Transistor current gain is too low in saturation for this state to be sustained, so the transistors begin to turn off. Again, positive feedback causes them to snap off rapidly, and the cycle starts over.