avatar

rsp

Member Since: July 23, 2007

Country: United States

Profile

Role

troublemaker

Programming Languages

all

Expertise

Creator of the Colorganic Spectralizer and Colorganic Spectralizer Kit (Sparkfun product KIT-10446).

Interests

meh

Websites

fearlessnight.com

  • It’s common practice to series connect small numbers of 18650 cells without charge balancing circuitry; just be sure to use matched cells (from the same mfr lot if possible) and start them out at exactly the same voltage.

    A good match for a 7.4V 2600mAh pack of these batteries is this one, which will charge the pack in about 4 hours.

  • This is a “Decade Resistance DIY Kit”. This is not a “box” since there’s no box, knobs, etc. But looks like it could Sparkfun the bench pretty well.

    For a beginner “decade resistance box” that really is a box, try the Elenco RS-500; it has a wider resistance range, finer resistance control, and more power handling capability.

  • Nice, now how about a “Q & A” column for questions about the product? There are many questions buried in comments that have never gotten answers; this feature might clean up the comments further and make the questions easier to address. And if you want to go all Amazon about it, you could also send out emails to people that have purchased the product so they could help answer the questions too.

  • Using 3.3V logic with the panel at 5V usually works, but not always. Using no level shifting won’t hurt anything, but to work reliably level shifting is required. Unfortunately level shifting does nothing to solve the ghosting problem; that one continues to haunt me.

  • The risks of using knock-off parts is that you don’t know what you are getting, but sometimes that’s okay. Often performance and reliability is not as good as a genuine part. So knock-offs can’t be used in production, but they’re fine for hacking purposes. I would prefer to see FTDI publish a “Genuine FTDI Identification Utility” so that I can tell if I’ve got the genuine part or not. The bricking strategy is far less useful to me and does discourage the use of FTDI parts in new designs.

  • It’s wise to be wary of unbranded batteries, but apparently Sparkfun did find a quality supplier for us. Test results for a brand new battery from Sparkfun today measured the actual capacity to be 2583 mAh (well within the datasheet specs). Test was 0.2C constant current discharge from full charge (4.21V) to empty (3.00V).

  • This is why we can’t have nice things. It doesn’t matter how many responsible drone operators there are because there will always be too many idiots (and maybe even a few terrorists) for the FAA to let drones proliferate uncontrolled. The hobby drone market may have to go the way that laser pointers went, so it’ll be illegal to buy/sell/possess any drone that’s large enough to hurt an airplane.

  • Apparently “Statistical Process Control” is not a phrase that’s popular at Sparkfun.

  • Here’s a nice picture showing the correct pinout, and here’s a better timing diagram.

  • S3 is on/off when the USB is disconnected. When USB is plugged in, you can’t turn this puppy off.