Monthly Archives: April 2019

You meet the nicest people on the Zoo

Yes, “on the Zoo” is a strange wording; the reason for it might become apparent.

This afternoon I went on a bike ride. I go on a lot of bike rides; most of them don’t really warrant mention (got on the bike, rode, went home). This one might have showed up on Facebook as I sometimes do, so that my riding friends can “like” the ride as an indication of their recognition of my awesome cycling prowess (not really), and the rest of my facebook friends can… well, I’m not really sure what they think of those kind of rides, though “what a nutjob” is probably a good start…

You can look at the – which I cleverly named “A Grand Squaky Zoo” after the three hills I climbed (Grand Ridge, Squak Mountain, Zoo hill) – here. 38 miles, 4186’ of up, which is a lot for me in April.

But I digress…

The climb up Squak was a bit more painful than I had hoped, and I planned on skipping the Zoo hill climb, but I had to ride by it on the way home and turned up the hill on the spur of a moment. And immediately thought I’d made a mistake, as the bottom part up to the Zoo is steep. I came around the first turn, and noted a rider up ahead of me.

That’s a good thing; riders up in front of you are rabbits and you can focus on getting closer to them.

As I drew closer, I looked at his bike, because a bike can tell you a lot. Steel frame, fenders, pretty wide tires, and a handlebar bag in the front. That’s a touring setup. But many touring cyclists don’t ride hills, which meant it was most likely a Randonneur. Randonneur is a long-distance cycling discipline with events that are pass/fail based on elapsed time, so a 200 kilometer event (120 miles, or nearly 1000 furlongs) must be completed in 13.5 hours. Which isn’t really that out-of-the-ordinary, except that 200 km is the entry-level distance and the routes tend to be more than a bit hilly.

Where it gets to be a bit nuts is rides of 300, 400, or even 600 km; the local Seattle International Randonneurs 600k route involves nearly 22,000’ of climbing, is 383 miles long, and as a 600k has a time limit of 40 hours. There are also 1200k rides with a time limit of 90 hours; in that time you will climb 38,000’.

I like hills, but that seems a bit excessive…

As I pulled up next to the rider – why am I quite a bit faster than a randonneur rider? – I slow down to talk to him. Any distraction is welcome on a long climb, and this one is going to take me 36 minutes today – so we start talking, and he mentions that this is a training ride for him; he rode over from Freemont and he’s going to ride up this climb 6 times and then go home.

6 times. Well, if I was going to ride it 6 times (for about 7000’ of up total), I guess I’d be riding it fairly slowly as well.

Turns out his name is Doug Migden, and he’s training for the Transcontinental Race, a self-supported race across Europe. In 2015, he rode the 4200 km and climbed 35,000 *meters* in 446.5 hours. There’s a great writeup of his experience here.

I often wondered what you do if a 1200k ride isn’t long enough, and now I know. It’s always nice to run into people that are crazier than you as it lets you feel that you are sane.

We chatted and I learned a lot about long-distance self-supported riders. As we got about 3/4 of the way, I turned left to head to the classic top of the climb. Normally I don’t think you have done the Zoo if you don’t do the top, but a) Doug was going to an alternate top, and b) he was doing it 6 times, so I think I’m going to cut him a little slack.

And damn, was that descent cold.

WS2811 expander part 5: 12V stress test…

One of the points of the expander is to be able to drive bigger loads than the 18mA that the WS2811 gives you directly. Much bigger loads.

To do that, I needed something that would stress the system, and I needed to verify that the design worked with 12V.

First off, I needed to cut a new stencil uses the paste layer:


That’s a bit nicer than the first one; there is adequate spacing between the pads this time.

Aligned it on the board, applied paste & components, and reflowed it. Here’s the result, still warm from the oven:


All the components self-aligned nicely, no bridges, no missing wires. Perfect.

The only thing I need to do is get rid of the center pad for the MOSFETs, since they don’t actually have a center pin.

How to test it?

Well, I dug through my boxes and found a 5 meter length of 12V LED strip. It says that will be 25 watts. I hooked it up and verified that all 3 output channels are working. It’s running an animation that ramps from 0 to 255 over 2 seconds, holds for 2 seconds, and ramps down for 2 seconds. I chose that because the quick switching is the hardest for the MOSFET to deal with from a heat perspective.

But 2 amps isn’t quite enough. I dug out a 12V power supply that claims it can do 6 amps and hooked it up to one output channel:


That’s the NodeMCU board in the upper right, powered by LED, the data and ground running to the board, and then some decently-hefty wires running to the board.

More load, more load, more load. I want something that soaks up the 12V. Incandescent car bulbs are nice but I don’t have any handy. But I do have an extra heated bed for my 3d printer; it’s a nice 6” x 6” pc board. Hooked that up in parallel with the lights:


Ignore the breadboard…

This worked just fine. The board heated up to about 170 degrees, the lights worked fine, and the MOSFET on the driving board just *barely* heats up. My measurements show that it’s switching about 5 amps of current.

The only one that’s not happy is my cheap power supply, which is putting out a nice 10Khz (ish) whine when under load.

I switched over to run it on all the time to see how that affected things. After 10 minutes, the board is up to about 110 degrees, the printer bed is up to 240 degrees, and the 12V power supply is 125 degrees.

I think I’m going to rate it at 6 amps total; that gives a lot of margin, and frankly 70 watts is quite a lot of power for this application.