# oren

Member Since: April 19, 2008

Country: United States

• This is not true at all. The rovers have always relayed their data to/from an orbiting satellite (Mars Odyssey, Mars Reconnaissance Orbiter) which then relay the data back to the Deep Space Network on Earth. The high gain antennas on these satellites are larger than the rovers themselves.

• This bears a striking resemblance to Siftables.
Don't expect too much from that solar cell...

• Very cool. But ARGH... Amps are not units of power! *&%\$&#!!!

• Are you sure you're treating your data correctly? I originally thought I was having a similar issue until I realized that it gives coordinates in degrees and minutes (with the decimal in the minutes number) rather than degrees and decimal degrees. This information is in the NMEA spec.
Plotting the coordinates on google maps gave me a location about 8 miles from my real location, but correcting the format gave me my actual location to within 10 ft.

• I don't know why this is being marketed as a solar cell. It's not... It's a photodiode.

• The voltage divider most likely wouldn't have worked anyway. You typically build voltage dividers with larger resistors so that you don't draw too much current. This is fine if you just need to change the range of a voltage that you're sampling, say with an ADC, since the ADC input is usually a FET that doesn't really draw any current.
But the whole point of a battery is to have a SMALL series resistance so that you can use it as a power supply, i.e. the voltage stays relatively stable no matter how much current you draw from it. Adding a voltage divider to a battery changes the series resistance from a few ohms to several kilohms (R1 || R2). This means that the voltage will quickly drop to near zero whenever you draw a non-negligible current from the divider tap.
You could use smaller resistors so that the voltage drop is smaller, but then your divider will be taking a battery voltage to ground through a small resistance, and your battery will be depleted even faster.

• It's extremely arduino biased. I honestly can't figure out why people have been making such a big deal about the arduino... you're paying \$40 for a \$4 microcontroller with a power supply and a built in programming cable.
Dev boards make sense for something like an FPGA or an ARM, where the only packages available are surface mount or BGA... It's really annoying to have to lay out a board or deal with complicated / expensive soldering techniques if all you want to do is play with the chip.
But AVRs are so stupidly easy to use... AND they're available in DIP packages. You can just stick one in a breadboard and have it talking to the computer in less than two minutes!

• I'll probably just end up soldering the backlight cable directly to my board since the connector is so hard to find.
Important note to anyone thinking of using this LCD though:
You need 28 volts at 20 milliamp to power the backlight. Don't just connect it to your standard 5V supply... you're going to need a boost converter.
To sparkfun: You guys went to the trouble of making the LCD test board in the picture... why don't you sell it?

• Any references for the LED backlight connector? I can't seem to find it anywhere...

• Is there a footprint for this part somewhere? I'm lazy...

No public wish lists :(