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.

  • 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.

  • If you put about 1V of resistance in the emitter of those bipolar transistors your matching problems are greatly diminished.

    I use current mirrors to drive LEDs when I don’t know how many, or what color LEDS or what battery voltage the customer is going to use. I just have a terminal labeled LED that I know will draw about 18mA from whatever positive source they have available.

  • I have a Tektronix TDS540 scope. When they were built they used 10V rated aluminum electrolytics on the 12V DC buses. Now after 15 years or so most of these scopes are dead. Some owners like me have replaced the 10V caps with higher voltage ones to keep the scopes running. So far I have replaced 66 caps on one PCB alone.

No public wish lists :(