Sherpa

Member Since: October 26, 2011

Country: United States

Profile

Electrical engineer, tinkerer, and general Maker. Professional work is mostly in underwater robotics and remote sensing.

  • Another way to deal with the reverse bias problem for the 5mm LEDs would be simply to put a small diode across the LED pins to short the reverse current. The bias resistor to set the forward current would also limit the reverse current to an acceptable value. No rectifier board needed.

  • It seems Eagle has changed the file extensions. Component side = .cmp Solder side = .sol Top silk = .plc Top mask = .stc Bottom mask = .sts There are also .gpi which looks like a photoplotter setup file. It does not generate a drill file as part of the CAM job. You need to run excellon.cam separately and add that file to the rest of the CAM files to have a board made.

  • Where do these Gerber files go? I opened the CAM processor, opened job gerb274x.cam, loaded my .brd file, it showed the path to my board at the bottom of the box, I hit “process job” and something happened with no apparent error messages. But I don’t have files with extensions like .GBL or.GTL anywhere on my hard disk.

    I have Eagle 7.3.0 Standard, Win 7

  • How hard is it to put an external antenna on it? I need to use a directional antenna outside of a metal NEMA cabinet.

  • As someone not too familiar with networking it took me a while to find I needed to use WLAN_SEC_WPA2 instead of WPLAN_SEC_WPA for a WPA-PSK network.

  • Is this board open source? I want to use it in a project that requires parts be available for at least ten years. Open source parts qualify.

  • I tried working with a similar chip a few years ago to make an underwater mouse and I found that without the specialized lens getting the optical alignment right was very difficult.

  • I can’t find the shortcuts file. The link http://www.opencircuits.com/SFE_Eagle_Shortcuts goes to “Open Circuits has a problem”. Googling ?sparkfun eagle shortcut? doesn’t turn up anything that looks likely. I see this tutorial is rather old. Should I be using another?

  • The skimpy datasheet doesn’t say anything about the antenna. Can I assume 50 Ohm output? Will it directly drive a ¼ wave whip? What sort of antenna are you using?

  • Yes, you need a supply voltage to accommodate the worst case number of LEDs. Any excess voltage produces extra transistor voltage and therefore extra transistor heat so try not to go overboard. The Vbe of bipolars varies less than the Vgs of MOSFETS so biploars match better so long as temperature is not a problem. With TO92 packages it is easy to glue two together for a cheap thermally matched pair.

No public wish lists :(