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Transistor Voltage Inverter Answered

I am a newbie and was hoping someone could assist me. Given the following schematic which takes a voltage of 12v and considers it off and a voltage of 2 volts and considers it on can someone tell me what changes would need to take place regarding capacitors and resistors (if any) to account for 20v instead of 12v? Meaning that when 20v is considered off and 2v is considered on.


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5 years ago

Something is definitely missing from this schematic...

The "output" (I assume that's the arrow on the right) might change, but there's no current source for Q2. Little or no current will flow from the base of Q2 to the collector (and for sure not 12V). Also--if there were a current source (for Q2 collector), the voltage would be "undetermined" unless we know what the load is on the collector. Even if it's digital logic, there needs to be a current source and a load resistor for the collector.

RE: the LED and switch--the LED will certainly be off when both ends are held to ground with the switch engaged. It would have an effect on the "output," but again--undefined, voltage-wise for sure.

Also--"Trans voltage inverter" (the thread title)-- each BiJ transistor stage in a common emmiter configuration will invert the output...I.E., the opposite of the signal at the base. Of course, On and Off (and inverted) can meananything (in this case, probably the state of the LED).

Don't know if that's a help--or not...