Hi, I have a project that I'm working on. The main idea is to construct a BJT/MOSFET circuit to turn an LED on or off. The project uses a 4.5V solar cell source connected to a BJT transistor. That BJT transistor will work as an open switch when there's no voltage detected from the solar cell, and as a short line switch when the 4.5V remains there (will reach the saturation). The collector of that BJT is connected to the gate terminal of an N-channel MOSFET (Enhancement mode). BJT will either ground the gate when it's saturated, making the MOSFET off. Or, turn the MOSFET on when it's open. I will attach my circuit so you can have an idea of what I'm talking about.
My question here... I initially wanted to do that with a JFET, but the circuit did not work. Is that related to the fact that JFET gate terminal will not be off when the BJT transistor grounds its gate (again, once the transistor reaches saturation).? Also, by looking at the circuit I attached, it seems like the 10k resistor acts like it's not even there when the BJT transistor is open (You will notice that the voltage is 0, hence the BJT acts as open switch). Any idea why is that?
Here's the video that I watched on youtube to do this project, it is pretty much what I wanted to do:
Thank you,
My question here... I initially wanted to do that with a JFET, but the circuit did not work. Is that related to the fact that JFET gate terminal will not be off when the BJT transistor grounds its gate (again, once the transistor reaches saturation).? Also, by looking at the circuit I attached, it seems like the 10k resistor acts like it's not even there when the BJT transistor is open (You will notice that the voltage is 0, hence the BJT acts as open switch). Any idea why is that?
Here's the video that I watched on youtube to do this project, it is pretty much what I wanted to do:
Thank you,