Late last week I received my order from Element 14. I got three Raspberry Pi boards and two Adafruit clear cases, with shipping and tax the total came 158 dollars U.S. and change. I already had my own keyboard, mouse, 5V AC adapter with a micro USB plug on it, a HDMI cable, and a
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I recently came across some of the pictures that I used in early my watsonseblog, sometime around the mid 2000s. From 2000 when white LEDs were very expensive and difficult to obtain, the LED flashlights (torches) were very expensive. Generally, a LED flashlight with a few 5mm white LEDs would cost several tens of dollars
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(Written by Watson “Watt Sun” Apr 24, ’05 – this was long before you could buy a cheap LED flashlight at the corner store.) When I first started making my white LED flashlights, I made some with four cell battery holders because I couldn’t get any three cell holders. Also I bought several regular 4
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I made this reed relay in May, 2005 and posted it to my late great watsonseblog. I think it hasn’t been posted here yet. It closes at less than a tenth of a volt, which is way too low voltage. This means I need many more turns of much finer wire. But it was difficult
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This JT uses a larger core that is typically found in low frequency applications such as EMI and RFI suppressors. This toroid has high permeability so it doesn’t take many turns to give a high inductance for a JT. The FT87-75 can be found at Surplus Sales for a dollar or so apiece. The 2SC2500
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Years ago I started seeing TIA or Thanks in advance at the end of emails and messages, and the thought occurred to me about what these people were trying to say. I’ve never used it, simply because it seemed inappropriate to me. I’ve always used thank you or thanks, meaning that I’m showing my appreciation
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A few years ago, there were news articles about the great potential of Graphene, a type of carbon or graphite. I would say graphene to someone and they would say, “do you mean graphite?” And I would say, no graphene – no one had heard of it yet. As this article says, graphene is being
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One of my email correspondents, Paul, has built a baker’s dozen of the Joule thiefs with LED light strings, but all were white LEDs. I have a few strings of Xmas tree LED light strings, but all of them are multicolored, and are the type that run off a battery pack of four AA cells.
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Chocolate? Paul has talked about using hot glue to hold the circuit to a ‘chocolate block’, but I’m not sure if that’s the same as the European style connectors we can get from Radio Shack. I did manage to find dark colored versions of them in a Google search, but the only color I’ve ever
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