Monday, April 22, 2013

Taillight trouble

The Serfas tail light that I got and tested last week developed a problem. After a couple of days riding in the rain, I noticed considerable condensation inside the light.  I sent this photo to Serfas and they immediately offered to replace it, so I must assume that this is not typical, but it's something to keep an eye on if you get one.

Tuesday, April 9, 2013

Another taillight, another test

I got a Serfas USL-TL60 in today.  It's my new favorite taillight.  It's not cheap at $60 but its performance is better than anything I've seen short of a Dinotte.  Honestly, I think this is probably as bright as I want to go - anyone who still "doesn't see you" with this sucker on your tail wouldn't see a neon green elephant.

I was surprised that it's brighter than the MagicShine.  I was also recently told that it was "the same LED as in the Cygolite Hotshot" - if so, they're either driving it harder than Cygolite does, or their optics are better.  Their optics are certainly better than the Hotshot at dispersing to the side, but clearly it's also significantly brighter even on-axis.

I think in the budget category the Hotshot is good.  I like the Knog Blinder but the mounting is pretty flimsy and non-flexible - you need a seatpost, period.  I've heard LOTS of people say their Knog mounts broke in less than a year.  Knog really needs to step up and make some lights that mount some other way than with a rubber band.

EDIT 4/10/2013 - first morning out, in the rain, I had the Serfas on the belt clip on my wedge pack, and it flew off when I hit a hole.  I don't think the belt clip is to be trusted at least on thin, smooth straps.


Saturday, April 6, 2013

Troubleshooting: Funduino

I picked up a Funduino Mega a couple of months ago - it's a clone of the Arduino Mega 2560.  I have it running my Prusa i3.  However, I have had one problem - it really wasn't properly operating unless plugged into USB - there was some kind of problem with the power.  This manifested when trying to print stand-alone from the control panel and SD card - the panel worked but was very faint, and the motor drivers didn't work at all.  If I plugged into USB, even just the hub with no computer, it worked fine.

I finally sat down and figured it out this evening.  The problem was that the 5V regulator that they used on the board was mislabeled - it was a 3.3 volt regulator.  So both 5v and 3.3v lines had 3.3 volts or thereabouts on them.

I hacked in a 7805 (see photo below), unfortunately lifting a pad in the process so I had to put in a bodge wire to take care of it.  It is hard on the board since it's designed for a smallish regulator and the 7805 is large and the pinout is wrong, which is why it's mounted in a weird way.

Anyway, the board is working fine now.  I should probably blob in some silicone snot to hold the thing in place so it doesn't vibrate the traces too much.

There are a lot of < $20 Mega compatible boards on eBay right now.  I doubt any of them have any better QC than the Funduino, so be sure to check this when you get your board, it can seem OK at first especially if you are using USB so the board gets its 5v from there.