2020-01-21, 05:06 PM
For the bootstrap capacitors, 0.1uF is too small. 0.33uF seems 'ok' but a larger capacitance is also ok, so 1uF is safe to use.
You can use various mosfets, I have tried several. Typically with about 70nC gate charge.
the resistor R1 is used to protect the arduino from short circuits. Without it, the cheap ams1117 regulator on the nano can pop. It also offloads some of the dissipation from the linear regulator and gives a few more volts of margin to the 15 volt maximum rating, and the diode gives a little more margin also.
The next version will have a buzzer.
You can use various mosfets, I have tried several. Typically with about 70nC gate charge.
the resistor R1 is used to protect the arduino from short circuits. Without it, the cheap ams1117 regulator on the nano can pop. It also offloads some of the dissipation from the linear regulator and gives a few more volts of margin to the 15 volt maximum rating, and the diode gives a little more margin also.
The next version will have a buzzer.