Skunk

Skunk is the project of building a box around the helium flowmeter for precisely filling balloons. It will:

Have a menu allowing the user to set a volume of helium to pump or a mass of balloon to lift (Integrating the balloon burst spreadsheet from http://cuspaceflight.soc.srcf.net/calc/)
Have a screen (2x16 LCD with LED backlight) displaying helium pumped so far, target amount of helium and current flowrate
Have a knob for adjusting helium flowrate
Have a sexy box with wheels including the (massive) batteries

Current status: Cillian has bought a significant proportion of the electronics parts and is playing with them.

Gas connections are all hooked up and (basically) sorted! Need testing though
Box is bought and gas stuff is largely fitted. Gas connections need panel mounting
Electronics needs boxing and proper cables/connectors adding

Things what need doing:

Random plans and pondering:

Arduino apparently has an upper limit of supply voltage of 20V, the battery supply is nominally 24V and the buzzer takes 12V - I figure take a lead off between the batteries and give that 12V supply to the arduino/buzzer and the full 24V just to the flowmeter with a common ground. I figure the power to the arduino and piezo is small enough compared to the 350mA flowmeter that the difference in drain between the batteries should be negligible.
Cheap keypads with numbers 0-9, * and # - I figure that's sufficient for a menu system with # as yes/enter/ok/start pumping, * as cancel/back/pause
Keypad comes pre-matrixed, arduino mega should certainly have enough pins for LCD, keypad, serial and other gubbins. An uno would probably need something more fancy and/or the serial display.
Arduino box needs to be at least: 110 x 60 x 40. Cillian will go to maplin and poke some boxes.

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