We have a project where our 2nd year students build an H-bridge controller from scratch. They learn a lot about power dissipation. We have a simplified design using IRF540 for the N-channel, IRF9540 for the P channel. These are way over-spec for the application, tiny robot motors. WE use 6V batteries, so to turn on the gate of the N-channel transistors we can use the output of the Arduino, and to turn on the gate of the Pchannel we set gate to 0V, or leave in a high-Z state with a pullup resistor.

This works. However, we were thinking of extending the exercise to show all N-channel. That's the way it's done at larger scale because the N-channel has such dramatically better on-resistance. I think the difference is 0.004 ohms vs. 0.113 ohms, so it's significant. This would require that we generate Vcc + 5V for the gate.

Is there a clean way to generate a tiny current at a voltage 5V higher than Vcc? We would like to have them build the circuit, not just use a black box.

We have a project where our 2nd year students build an H-bridge controller from scratch. They learn a lot about power dissipation. We have a simplified design using IRF540 for the N-channel, IRF9540 for the P channel. These are way over-spec for the application, tiny robot motors. WE use 6V batteries, so to turn on the gate of the N-channel transistors we can use the output of the Arduino, and to turn on the gate of the Pchannel we set gate to 0V, or leave in a high-Z state with a pullup resistor.

This works. However, we were thinking of extending the exercise to show all N-channel. That's the way it's done at larger scale because the N-channel has such dramatically better on-resistance. I think the difference is 0.004 ohms vs. 0.113 ohms, so it's significant. This would require that we generate Vcc + 5V for the gate.

For a teaching circuit, with a power side of 12V, is there a simple, clean way to generate a tiny current at a voltage 5V higher than Vcc? We would like to have them build the circuit, not just use a black box.