Why is my Transistor Reducing Voltage in Buck Converter Modeling?

AI Thread Summary
In modeling a 5-12Vdc buck converter, the addition of a transistor between the output resistance and the diode unexpectedly reduces the output voltage significantly. The transistor, despite being a closed switch, is consuming a substantial portion of the voltage. The discussion highlights the importance of understanding the voltage at the emitter of Q2 relative to its base, indicating that a high DC gain is necessary in this scenario. Additionally, examining the characteristics curves of the 2N2222A transistor is recommended for better insights. This situation underscores the complexities involved in transistor behavior within buck converter circuits.
Chacabucogod
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Hi I'm currently modeling a 5-12Vdc buck converter, and just out of nowhere decided to put a transistor between the output resistance and the diode. Now, this transistor is always connected to voltage so it shouldn't do anything at all, it's just a closed switch. What happens is that the transistor ends up eating a lot of the voltage. I don't really understand what's happening.

Circuito.png
output.png

Resistance Voltage. It's 2... when it should be 12.
 
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Actually it's a boost. My bad...
 
What is the V at the Emitter of Q2 Relative to the base of Q2?
 
Looks like that a demand for a transistor DC gain (Icollector/Ibase) must be pretty high in this example.
Check out 2N2222A transistor's characteristics curves.
 
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