MOSFET Wiring diagram for 2-button, dual voltage?

[Charged]

Atmel AVR > pic IMHO.
Some people think the fastest Microchip PIC (20 MHz 4:1 pipeline) is as fast as the fastest atmel AVR (20 MHz 1:1 pipeline). They are wrong. The PIC is actually processing instructions at 5 MIPS and the AVR is at just under 20 MIPS. Also, the AVR instruction set is larger, so in many cases, it is getting more done in fewer cycles.

 

[candre23]

Speed isn't really a concern here. All the chip needs to do is

• recognize user-entered setpoint adjustments via up/down buttons
• output setpoint to LCD display
• generate PWM signal to switch FET
• monitor output voltage on analog input
• modulate PWM output based on feedback from analog input

Pretty much any microcontroller with enough IO pins can handle that. The main concerns are size and price. At 18mmx33mm and $19 respectively, the Arduino mini is hard to beat.

The only part I'm still iffy on is the LCD display. I'm having trouble finding one that's small enough. I may just have to rip apart some cheap digital watches or something.

 

[Charged]

agree speed is not of the essence if your only doing voltage control

 

[candre23]

Maybe this for the display? $20 is a lot for something like this, but the size is right and I like the idea of an alphanumeric readout.

EDIT: Score! No point in doing this half-assed. Might as well go all out and use a 128x32 graphical OLED panel. 27mmx14mm and only $19! There's room for a huge amount of information on this display, so I could easily add features like battery voltage / est. % remaining. This is moving from thought experiment to actual project, so I should probably start a separate thread for it once I have it fully planned out and parts ordered.