Sunday, July 19, 2009

PPAC Progress: UP!

I've been working on (mostly) minor tweaks to the alarm clock:
  • The can I had used to test mounting techniques served its purpose as a prototype, so I redid the mounting in a fresh can, with adjusted positioning of the LCD and (new) lit button, with use three screws per end cap instead of two. I scanned the LeSueur label and printed a copy to test the positioning of the LCD, button, and power/relay port cutouts.
  • I over-tightened the plastic ring which opens the output valve of my 10-gallon air tank, leaving me with a sealed can at 105psi! I bought a 5-gallon tank as a replacement, figuring it would be fine for a full run, and was impressed by its lightness. I "fixed" the 10-gallon tank's valve by cutting off the plastic ring, so I can turn the open/close with a small wrench, so now have 15 gallons to pressurize.
  • Testing the 5-gallon tank at 100psi, the plastic "open" safety valve popped a leak, so today I replaced all pre-solenoid valve hardware with brass-- no more leak!
  • Since the emptying valve didn't get enough pressure from the inflated "pea" to open, I replaced it with a manual valve-- not as elegant, but the alarm is about inflation, not deflation.
  • The alarm was still triggering when the alarm was "off" and the target time was reached, plus there were a few small bugs to work out.
  • The maximum inflation time was set arbitrarily at 30s, so I added another click+hold "hidden" mode branched from the alarm mode selection so the max inflate time can be adjusted. It's also stored to (Arduino) EEPROM with other "system" parameters.
The IDE tells me I still have a little headroom:
"Binary sketch size: 13566 bytes (of a 14336 byte maximum)"
I'm tweaking the program a but more, but it's late and I'm so happy with how far it has come! I plan to be woken up rudely in the morning...:D


  1. More complex control systems using valves requiring automatic control based on an external input require an actuator. An actuator will stroke the valve depending on its input and set-up, allowing the valve to be positioned accurately, and allowing control over a variety of requirements.

  2. Not sure I follow the gist of your comment, IE-- the output here is to a relay which pops a sprinkler valve, an on-off operation. Industrial control valves are very expensive so I opted for hardware store components, but I have a leak so perhaps need to look at other options.