Two Trans. Osc.

392

09:02:48

Can anyone tell me why this circuit is not oscillating? (See https://www.circuitlab.com/circuit/6djt8a/two-transistor-oscillator/)

published 11 years ago

Voltransistor

11 years ago

Wouldn't it short out from the PNP transistor to the base and emitter of the NPN transistor?

antilogues

11 years ago

Ah, thank you. I had put the cap. in the wrong place. Works now. :)

Voltransistor

11 years ago

Your welcome! :-) And Thankyou!

antilogues

11 years ago

I am still getting very bizarre readings with this circuit though. Sometimes the V at the PNP base node peaks at 40V? Do you find that this simulator is very buggy?

thebugger

11 years ago

No its not buggy that is just the junction capacitance taking a toll. It is normal.

thebugger

11 years ago

If there was a way to disable it you'll see that everythings normal.

hurz

11 years ago

I don't think there is any electrical explanation here for this behavior. A single capacity can not cause a voltage jump from 5 to 40V. With caps you can just add voltages, so adding 2 times 20V to around 40V, or stacking 8 times 5V to 40V. But there are not enough caps to do so. I guess its more related to the simulator and the taken simulation speed. This circuit has a very sharp transient point which is hard to catch for the simulator especialy if the sim speed is to low. The sim speed is ok for a full periode of this oscillator but much to slow for one of the transients.

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