Tuesday, August 23, 2011

New tool time. An O-silly-scope. - A DSO Nano v1.5

I've got piles of voltmeters. Most of them are hilariously cheap, but when an accuracy of .1v is enough, the $3 voltmeter from harbor freight will do the job.

Voltmeters are grand, but they are very poor at showing you charge and discharge curves, and tell you absolutely jack about waveforms. That's where an oscilloscope comes in to play.

I have been lusting over the pocket oscilloscopes for a long time. And slowly the price has been coming down to the "why the heck not" level. About two weeks ago I decided that a DSO Nano had to be mine. $66 later, and four days of waiting, and it was.

Well there we go. You also get a little felt bag and a USB cable. But those are the big things you get in the package. No documentation at all!

They claim that it will accept 80v peak to peak. And that it has a 12bit DAC. Also they claim that it's got 1Msps.

I figure that means I can reliably look at 100khz signals.

On the subject of signals, it has this nice little test point on it. The test point is adjustable from 500hz to 2000hz.

Here's the DSO checking out it's own test signal. You can see it overshoot and the discharge curve. I wonder where that tail is coming from...

Now I wanted to try it with a really fun. The only thing I could think of that I had that would output a nice signal was my arduino. I loaded up the servo sweep sketch, and checked it out.

The servo signal is a pulse, every 20ms, that's between 1 and 2ms wide. I made a video of it. http://www.youtube.com/watch?v=YlIW7AvBg0Q

I posted on the EEvblog forum, asking for ideas of how to test, and exercise it. http://www.eevblog.com/forum/index.php?topic=4546.0

So it looks like I am going to make a joule theif.

Monday, August 22, 2011

How do you accidentally visit a motorcycle museum?

Well, that's a simple question to answer. When the museum is also a motorcycle shop. The place is the wisconsin motorcycle museum.

Here's a few pictures, since I was surprised, I didn't have my real camera with me. Excuse the quality.

Great, I get to start off with a bike I can't identify. I promise to get details on my next visit.

A Maico 490. There were two of them!

A custom framed and bodied Guzzi. I've never heard of this guy before, but there were several in the shop. A Magni Sfida 1000 4v

The other Maico

A Honda Dream 50

Another Magni.

A Bimota Tesi 3d

An I don't know what the heck it is, but the air intake is your crotch... :-)

And a shot of a bunch of bimotas, specifically a Tesi 2d.

I will be going back, with a flash, and a real camera.

Wednesday, August 17, 2011

Training Ride 8/16

24.6 miles. 15.2mph average. Not to shabby for a training ride. Especially when my last one was like .. 12mph.

Friday, August 5, 2011

Lights, and lighting.

I have always liked flashlights. When I was a kid I'd wire up extra batteries, and see how bright I could make a bulb. I also had a small collection of maglites, mostly the 3D size stuff. Given the time, and technology, it was about the best one could do without actually carrying a billy club.

Riding bicycles at night requires headlights. Simple? eh?

Well, not so simple. Bicycle headlights are expensive. Very expensive. And i'm a cheap bastard. Also, the cheaper lights tend to be incandescent. Which means 90% of the power will be radiated as heat. That's just not ok in my eyes.

The first headlight I bought, came with the taillight I have on my LT1000. It was (and still is..) a EL120 from Cateye. It's really not safe at any speed more than six or seven mph in the dark. Soon that was followed by a EL210. Which had 5 LEDs. And that actually is a useful light.

I did some research, and found the cheapest (electrically) way to make light is to use LED's. And the cheapest way to make power to drive the leds is with a switch mode power supply. (SMPS) I ended up buying the cheapest per-lumen leds I could find. I ended up building a national semiconductor simple switcher based circuit to drive them.

I was so proud when that little breadboard test worked.

The whole schebang was wired up on some perfboard, and made to work. But I made lots of mistakes, and I couldn't come up with a satisfactory mounting method. In the end I had 60 led's on perfboard with a PSU, and a grid of resistors to make them not burn out. Pretty terrible really.

Soon I learned of dealextreme. And I ended up buying some flashlights through them. the first ones were some AA "lock blocks."powereed lights. And I would attach those to the bike using something called

The choice of AA's was in a large part due to my desire to use normal batteries in the flashlights. And I had a decent stockpile of NiMh batteries to throw in them. The flashlights I bought were claimed to be "3w." Later, when I got my new flashlights, I found that they were only actually drawing 1.2watts.

They were just fine, and so long as I had two of the flashlights going, I was feeling pretty safe riding up to 15mph or so. But as I got faster, 15mph didn't cut it. So I started searching.

I think the big thing that made me buy into the 18650 size flashlights was the fact that I had a laptop battery with a dead controller board in it. The cells were all just fine, so I knew I could scavenge them. Around that time I was also just starting to get "ok" with LiIon cells. (I still distrust them on a certain level. I don't like cells that can catch fire.)

I took the plunge and bought a set of WF-502B based lights from Dealextreme. They claimed to be 250lm. These were the brightest things I've ever had my hands on. They were supposed to be a little more than twice as bright, but these things leave streaks across your vision if you look at the spot of light when shone at a desk! The kicker, is that they actually draw 4.2 watts!

Where I needed both lights going to feel comfortable with the older AA powered flashlights, just one of these 4.2 watt flashlights leaves me feeling warm and fuzzy while riding at night. Even up to 20mph or more.

This little setup has served me well for the last two years. Lots of light, and lots of battery life. A 2500mah 18650 LiIon cell lasts a little more than two hours.

Monday, August 1, 2011


Tonight I put new pedals on my folding bike.

I'm going to try to take it to work on the train tomorrow. In theory metra allows you to take a folding bike on the train at any time. However.. this bike doesn't fold that small.

It's all farkled out now. I have a computer and lights on it.

I should have bought this instead: http://www.foldingbikeoutlet.com/shop/citta-16-folding-bike-apex.html

Then again, it wouldn't have been $75.