Npn-Pnp transistor switch.

145

02:04:44

This circuit shows how an Pnp-Npn set of transistor is turned on.The base of the Npn get "Pulled UP" and when it happens, the base of Pnp gets "Pulled Down" over the Npn.With this configuration we can connect our load to ground.(ground returned load).
And we can discard base-collector 180 phase difference.Because we connect our load to pnp collector.

published 10 years ago

hurz

10 years ago

The NPN transistor is in dangerous to be destroyed! Because of the high base current. It needs at least one more current limiting resistor e.g. 4.7kOhm. For a fast and safe switching it also needs a pullup for the PNP, cuz the base is floating in case its not pulled down to ground by 10k. Keep it up.

mehmet1989

10 years ago

Yes that is true.Thanks for you advice.

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