Electronic – Relaxation oscillator

bjtoscillator

I was wondering how inside the relaxation oscillator heating is not produced inside the BJT junction causing destruction of the transistor.

schematic

simulate this circuit – Schematic created using CircuitLab

and this is what I propose:

schematic

simulate this circuit

Best Answer

Heating IS produced inside the transistor. You can easily calculate how much (voltage × current, averaged over time), and show that it is well within the transistor's ratings.

You can't substitute a zener diode for the transistor, because it doesn't have the negative resistance characteristic that the transistor has.