| Electronics > Beginners |
| Series Voltage regulator |
| (1/1) |
| BayHitchi:
Hello people, im a begginer in eletronics and my first project is a series voltage regulator with overcurrent protection. For some personal reasons i coud not attend school for some weeks, so im pretty lost in transistors and regulators. I dont ask for anyone to just do it for me, but if ayone could help me out understand how/why to project it woul be amazing! I just have to project the values of all resistors, V(in)max and V(in)min, in this circuit. The target V(out) = 12v and max current = 1A. |
| Seekonk:
At what voltage will the transistor turn on, then solve for resisyance. |
| not1xor1:
--- Quote from: BayHitchi on June 25, 2018, 09:12:54 pm ---Hello people, im a begginer in eletronics and my first project is a series voltage regulator with overcurrent protection. For some personal reasons i coud not attend school for some weeks, so im pretty lost in transistors and regulators. I dont ask for anyone to just do it for me, but if ayone could help me out understand how/why to project it woul be amazing! I just have to project the values of all resistors, V(in)max and V(in)min, in this circuit. The target V(out) = 12v and max current = 1A. --- End quote --- Tr2: as soon as the base voltage (ouput voltage divided by the R1+VR1+R2 divider) gets above the zener voltage plus Vbe, Tr2 reduces the base current of Tr1, while it does the opposite if the voltage gets below the reference (Vzener+Vbe). In other words, Vzener + Vbe is the input signal, while the base of Tr2 gets the feedback signal and adjust the amplification of Tr1 in order to keep the output voltage constant. Tr3: as soon as too much current goes through R5 (i.e. I * R5 >= Vbe), it "steals" some base current from Tr1 limiting the output current. If the current is below that threshold (it is a soft knee) Tr3 does nothing (it is off). knowing all the parameters (voltages, transistor features, etc.) you can easily calculate all the resistor values |
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