With inspiration from Ladyada's DIY boost calculator, I'm attempting to build a simple, low-current (<50mA) 40V boost circuit to drive an antique voltmeter. The PWM source for the transistor will be an AVR that can operate on as little as 1.8V, so that's the minimum voltage I'm targeting. I've been prototyping with a BC547 (BJT NPN) and a 5V supply, but I'm not able to get more than 36V with the components I have on hand, possibly due to an undersized Schottky diode.
I have a rudimentary understanding of BJTs but I've never worked with FETs, and I'd like to learn more. For this specific application, I believe I'm looking for a power MOSFET with a relatively low on-resistance. Max Vds should be well in excess of the 40V I want to produce.
Should I be looking at the gate-source voltage threshold (Vgs(th)?) to identify a FET that will work at the 1.8V I'm targeting? Filtering on that parameter lead me to this STP60NF06L, but the Output characteristics graph (fig 5, p6/16) shows that the current is extremely limited at that voltage, and may not be within the operating margins of the device.