Monday, 26 May 2014

Happy Days! – New eBay Order Arrives

Today, I received three of my eBay orders. The 0805 120Ω resistors, the 0805 white LED and the MAX7219ENG LED control chips.

Picture 49

This is the LED from the bottom. the tiny arrow indicates the anode (positive) and cathode (negative) side of the LED. The arrow points toward the positive, just as it does in the schematic for an LED.

Picture 50

I took one of the LED out of the packaging and gave it a quick test (multimeter on continuity test) to make sure that the LED was “live”.

Picture 51

This means, simply to touch the negative probe of the multimeter to the cathode end of the LED and the positive probe to the anode end. For those of you with a classical education “Fiat Lux” … for the rest of us “Let there be light”.

Picture 52

The resistors are the same length as the LED, but they are wider. The markings are right, I haven’t tested them yet … but I am confident that these resistors are OK … maybe that’s a little optimistic of me but, whatever, they only cost me peanuts .

I got 50 x 120Ω 0805 resistors for $1.33 AUD from citybestbuy, the 50 x 0805 LED (Super Bright White) were $2.41 from yankee_electronic. The 10 x MAX7219ENG I bought at auction from gc_supermarket for $5.34.

These orders arrived < 13 days from China to Tasmania, so I am a happy eBayer today.I should really have bought 100 of each of the resistors and LED, but then, I really only bought these so that I could try my hand at hand soldering SMD components. If I think that I can handle this form factor, then I’ll get some more or I may have to get the next size up. As I have said before, my eyes aren’t all that good any more.

I knew that the 0805 SMD were small, I knew their size because I checked and rechecked various online sources so that I’d have a good idea of their package size, but really? Now that I actually have some actual 0805 in my hand … they are VERY small indeed!

I’m going to try to whip up a simple 4 x 4 LED PCB and have a go. Not tonight, though.

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