My new bike is here! I decided to get a Montague Paratrooper, because it is the only full-size folding mountain bike on the market. I was looking for a reliable bicycle that would also store conveniently in the trunk of my car.
The Paratrooper is great bike! I put some street tires on it and it’s a great commuter bike that comes out of the trunk and re-assembles in less than a minute.
Last week I found myself in need of a USB toggle switch. Such a device would allow me to toggle the power on a USB device without having to unplug it. It is true – I suffer from a disorder that requires me to construct a USB switch rather than simply unplug my devices.
This simple device uses a USB extension cord and a slide switch connected to the +5V power line (the red wire). If you happen to have a device [such as an external video card] that requires to be reset every few days, simply toggle the switch when a reset is needed.
Now that I think about it, an “momentary off” switch would have been even better. Maybe I should think about the market here….
I have been on a bit of a quest to observe the sun effortlessly, without discomfort, and with my own eyes. There are plenty of great photos and videos of the sun in different wavelengths, but experiencing the sun without any digitization or intervening detectors has been a goal of mine.
I can finally report the combination of filters that allow anyone to comfortably view the sun.
For these glasses, the neutral density filters were attached to the inside of the welding shades using hot glue. Make sure to check the day’s sunspots when you go solar viewing. If there are big enough sunspots, you can see them!
My favorite source of sunspot infomation: solarham.net
![sunspot guide, solarham[dot]net](https://gregorykimball.me/wp-content/uploads/2015/10/sunspot-guide-solarhamdotnet.png)
I’ve been spending a lot of time on the Caltrain and my impression has been generally positive. If the SF bay area cannot manage to get public transportation working in the peninsula, at least there is a competent private transportation alternative.
Sometimes the congestion is just ridiculous, which inspired me to take this picture. You can’t easily tell, but I took this photo from inside the bike car while I was trapped and being shaken around for 30 minutes. And I paid good money for the experience! What a world.
I just completed a purchase of some additional crude oil samples to add to my collection. Here is my new favorite:
I like this sample for the large volume, the sturdy container, and the extra sloshing room in the container. I do wonder though… can I trust the “Guaranteed Texas Crude Oil” sticker? Hmm.. what nondestructive techniques could confirm the authenticity?
We have two 300W halogen flood lamps in the house, but I decided it was time for an LED upgrade. I selected the Cree 18W (90W equivalent) flood lamp as the replacement. I wanted to keep the 6ft tall lamp stand and dimmer, but remove the halogen housing, thermal runaway circuit and reflectors.
First, it’s time to remove some halogen components. In this picture we can see the metal guard rails, the quartz UV blocking pane, the halogen bulb, the ceramic contact housing, and the reflective base with thermal runaway sensor.
Now we’ve got the lamp to it’s bare live and ground wires, and we are ready to re-assemble the lamp with LED components.
And we’re done! Now we have an LED flood lamp attached to our halogen stand.
I’ve been having a hard time finding oscilloscopes and adjustable power supplies in the “hobbyist” price range, but I think I have cobbled together a solution.
A few key components:
Here is a recent test that is perfect for the components listed above: characterization of the DC buck converters for car USB chargers. In this test, I am measuring the operating frequency and ripple of an Adreama 1A USB charger. The charger is hooked up to the 12 V rail of the power supply, and the 5V output is applied to a power resistor as the load.
As expected, the performance of the charger is a strong function of the load. In this case, a 5 ohm power resistor is drawing 1 A from the charger. The buck circuit is operating at 50 kHz, but with 0.4 V of ripple. Ouch!
I recently took a trip to Alcatraz island to see the @Large Ai Weiwei art exhibit. On the way to the island, I was delighted to find that my ferry was solar-powered!
My excitement was only slightly tempered when the energy dashboard in the cabin showed that the PV output was just enough to power the lights…. The boat is actually diesel-powered, but I won’t stop somebody from doing a good ole green-washing!
One of the perks of having a modern vehicle is that you can use devices to monitor the engine and drive train performance. I was recently using my Vgate Bluetooth Scan Tool OBD2 Scanner to record speed and engine RPM values during a short trip. In the following plot, you can clearly see the six gears of the automatic transmission as straight lines in speed vs RPM.
The color coding shows the absolute throttle position, which shows 2nd and 3rd gear most used during high acceleration.
Sweet!
Here is the color wheel used by my electronic instrument, Abella. When the music box is playing “C”, the pitch display appears yellow. Middle “C” is set at 262 Hz, high “C” at 523, and low “C” at 131 Hz, and each is displayed yellow. The remaining notes occupy a RGB-CMY color space.
I think I like the color wheel even better as a “circle of fifths” :
Gregory Kimball 