Archive for April, 2015:

2015-04-29 Power LED Heat Sinks

I have been looking for something like this for awhile.  I bought a bunch of 1 watt LEDs without the ‘star’ mounting plate, and I have been gluing them with thermal glue to aluminum and copper heat sinks that I have made from scrap and 6 AWG copper wire.  I think these heat sinks from

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2015-04-29 Humongous Rectifier Diode

I ordered a half dozen of these huge, high current rectifiers from Goldmine for use as paper weights.  That’s about all they can be used for until I find some specs or a data sheet for them. The metal base is 3 inches or 76 mm square. I have seen rectifiers much smaller than this

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2015-04-28 Variable Power Resistor

Often I have needed a variable resistor with a power rating of up to 10 or more watts and a resistance of several ohms up to 100 or so ohms.  These are expensive and hard to find.*  I’ll explain how to make an inexpensive one, but first I want to explain what I have used

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2015-04-27 LED Filaments (Designing With LEDs)

The author of Designing With LEDs has been especially busy with posting interesting articles lately.  This article is about LED filaments from a Chinese seller.  Closeup photos show the insides of the LED strings.

2015-04-25 Transistor Tester Kit Does More

A few weeks ago I ordered this kit on a whim, not knowing what to expect, just something to assemble and get some soldering practice (this is what it looks like). There are several Chinese vendors that sell them.  The info claimed it tested other components besides transistors. It shipped from China so it has

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2014-04-21 Man Shoots Computer

It’s a Dell.  Man, I’ve known that feeling a number of times! I’ll bet the guy took the cover off, took it out and shot at it, then put it back on. There’s nothing wrong with the PC except it’s got a few more ventilation holes!

2015-04-20 New Cree T8 Fluo Light Replacement

Designing With LEDs has a new review of a Cree LED T8 fluorescent light replacement. http://www.designingwithleds.com/the-new-cree-tw-series-led-t8-review-and-teardown/ The price has dropped significantly – from $30 US down to $22 US per tube. One important thing that I got from this review is that the old ballast decreases efficiency and wastes power, so it’s better to rewire

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2015-04-19 A Way To Check For LED Lamp Life

I was reading that someone speculated that LED lamps may fail before the 25 thousand hour ratings claimed by many manufacturers.  This can be caused by failure of the circuit that drives the LEDs, not the LEDs themselves.  The most likely components to fail are the electrolytic capacitors, because they dry out or leak the

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2015-04-18 Spectrometer On Your Keychain

I’ve been playing, er, experimenting with Geiger Counters recently, just to satisfy my curiosity.  My mind’s curiosity area went into hyperdrive when I found out about this device.  Just think!  A detective could examine a hair to check for arsenic to see if the victim has been poisoned!  Wow!  I can think of other, less

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2015-04-17 Power Plug, Switch

I do exercise, but when I’m reading couch potato style, I like to have my LED lights with a switch close by.  So I make up extension cords with a plug, switch and outlet socket. I also like to put the on/off switch where the AC power comes into the adapter because there will be

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