Sherpa

Member Since: October 26, 2011

Country: United States

  • Tutorial - Beginning Embedded Electronics - 8 | about 2 months ago

    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?

  • Product WRL-10534 | about 3 months ago

    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?

  • News - According to Pete: Curren… | about 3 months ago

    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.

  • News - According to Pete: Curren… | about 4 months ago

    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.

  • News - Why You Should De-Rate Ca… | about 7 months ago

    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 :(