If I don’t make a list of everything I need to get, I’ll end up waiting on a parts order before I can finish a prototype, or worse, leaving something off the design entirely.
ICs:
- Atmel Atmega8 or Atmega168 for Arduino/Freeduino
- USB interface chip?
maybe only if USB is going to be externally accessible; could use LadyAda’s FTDI USB cable if willing to get inside to reprogram - voltage boost / regulator
- battery charging controller
maybe LM3622 used in the WaveBubble - Allegro A6276 16-bit LED driver
- digital resistor for LED current reference and dimming?
or could PWM A6276′s enable line — I probably like the PWM idea better - accelerometer / tilt sensor
sample the cheapest one I can find and make sure it’ll work — probably a thermal - Dallas RTC
- temperature-compensated crystal oscillator for RTC
- *PROM for fonts for POV mode?
- EEPROM for saving configs and POV text?
- LM34 Fahrenheit temperature sensor?
Other:
- ultrabright 5mm LEDs with > 30° viewing angle (15° half-angle) and prefer > 10,000 mcd
- very slim high-energy-density battery
16 LEDs * 25mA/LED = 400mA, so well over 400mAh for an hour of runtime at full brightness - coin cell and holder for RTC chip and oscillator
- watertight mini-USB connector for tethered charging and reprogramming???
- photoresistor or LED for light detection (maybe several around the edge?)
I’ve kind of dropped connectors for remote wired control, and wireless for a keyfob control. How much do those matter?
I’m curious about the tethered charging and reprogramming. I was looking to do this on one of my Arduino projects as well. I saw in a previous post relating to the charging circuit and looking into the Chumbys, I didn’t know those took a charge, as they don’t even come with a battery. LED PUCK = AWESOME!
I don’t know if these would be useful for your puck, but there are some Chinese vendors (and I guess US ones) that sell high power Cree LEDs and other LEDs that are much brighter than the 5mm LEDs for $3 to $10 (US).. This Cree XR-E 7090 Q5 bin is currently one of the brightest (PDF specs). With 3.7Vf at 350ma, they put out 107lm. They also sell inexpensive driver circuit boards.
I’ve bought parts for modding flashlights from two of them, DealExtreme.com and Kaidomain.com. The one disadvantage is these vendors take 4 to 6 weeks for delivery.
Leslie, thanks for the pointers. I have some 5mm LEDs on the way, as well as a couple of Luxeon-like LEDs and some real Luxeons at home. I hope we don’t need Luxeons for adequate brightness — I’m worried about the power density of the battery. But I’ll keep those in mind.
Instead of the USB interface (which requires a connector, which will cause problems making the device water resistant), have you considered an optical link?
Dave
Dave, I’m really enamored of the idea of USB charging. As fun as it would be to put a solar cell into this puppy so it could be laser-charged, I don’t think that’s very practical.
I’ll probably settle for a mini-USB connector, put a lot of silicone goo behind it to make it watertight, and be pretty careful about isolating the connector from the rest of the puck when it might be immersed. I really don’t want a LiPo battery discharging rapidly through impure water . . .