Tristan369
- Oct 29, 2020
- 32
- Joined
- Oct 29, 2020
- Messages
- 32
Hi I'm just trying to learn about basic logic gates with transistors, I started by using BJT's, and I had to learn that it sometimes needs voltage division because the current going into the base flows through it and otherwise sets the output high. This voltage division is very inefficient as well as just having the voltage drain through every transistor base.
I found out that MOSFET's don't do this, current does not flow through the gate and source, so you don't need voltage division on AND gates.
So I pulled one of my IRF3205's out to experiment and it does not work at all like I expected. Once voltage is brought to the gate, it just stays on... Even after disconnecting all power to it and reconnecting, it basically acts as non-volatile memory... I need to bring the gate to ground to turn it off. Is this specific to the IRF3205? Or is this with all MOSFET's? I started up this circuit simulator I use and the simulated N channel MOSFET's work exactly as I would expect them to. They don't need to be "turned off" like my IRF3205. They are only on when voltage is brought to the gate.
And are MOSFET's actually the way to go? Are they faster than BJT's? I'm thinking about purchasing some 2n7000's. Thank you!
Working in the simulator a little afterwards and it looks like you need voltage division with MOSFETS too? Otherwise current just flows through the MOSFET like its on?
I found out that MOSFET's don't do this, current does not flow through the gate and source, so you don't need voltage division on AND gates.
So I pulled one of my IRF3205's out to experiment and it does not work at all like I expected. Once voltage is brought to the gate, it just stays on... Even after disconnecting all power to it and reconnecting, it basically acts as non-volatile memory... I need to bring the gate to ground to turn it off. Is this specific to the IRF3205? Or is this with all MOSFET's? I started up this circuit simulator I use and the simulated N channel MOSFET's work exactly as I would expect them to. They don't need to be "turned off" like my IRF3205. They are only on when voltage is brought to the gate.
And are MOSFET's actually the way to go? Are they faster than BJT's? I'm thinking about purchasing some 2n7000's. Thank you!
Working in the simulator a little afterwards and it looks like you need voltage division with MOSFETS too? Otherwise current just flows through the MOSFET like its on?
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