To my knowledge Kingelectronics is currently the sole distributor for Macroblock LED drivers in the western world. They have quite a few interesting chips, e.g. the MBI5168. It’s an 8bit shift register with included constant current sink drivers. Just one external potentiometer is enough to adjust the current from about 5 to 120mA per channel. With three of these you can easily drive 8 common anode RGB LEDs and simply balance the colors with the potentiometers. As the outputs are current limited, you can also parallelize them if you need to switch a bigger LED. Proper thermal design required. This chips is ideal for Arduino users wanting to drive somewhat bigger LEDs at a reasonable price. The MBI5168 chips are used in Seeedstudio‘s Rainbowduino BTW. Other LED drivers are available as well.

If you find something of use in their list, you can join. But I only accept requests from inside the EU to keep shipping costs down. And as usual, I’m a hobbyist and no big business ;-)

Here’s the math for calculating the price per chip and the final one:

• price of a single chip in US$ as per Kingelectronic’s website.
• price of the chip in € including all import costs that I have to pay.
• shipping costs for importing the whole order (current estimate: 30$).
• shipping cost from Me to You in € (somewhere between 1.45€ and 3.00€).
• 1€ handling. carton, envelope, tape etc.
• number of parts for a certain component (i) (whole order).
• number of parts for a certain component (i) (yours only)
• import tax in % that I have to pay for the whole order (parts + shipping, 19%)
• number of different components
• component (i)
• €/$ ratio on January 14th 2010
• price in € for your parts including shipping from Me to You.

So the chip price is calculated from the original chip price + percentaged shipping costs and all import fees there might be. The percentaged shipping costs are weighted by the chip’s price. If the chip is cheap, only a small part of the total shipping cost will be added. If the chip is expensive, more of the shipping cost will be added.

Example order (no real prices, just easy to calculate):

• Part A – total order 100 pcs – 0.50$ each
• Part B – total order 10 pcs – 5$ each
• Part C – total order 1 pc – 50$ each

Each component contributes with 50$ to the whole order, therefore total shipping costs would be split into 3 equal chunks of 10$. If shipping cost 30$, the price (before tax and import) for Part C would be 60$, Part B: 6$ and Part A 0.60$. I hope that can be considered as fair.

You can chose other parts too of course.

Once again, this is a ‘hobby-level’ order and I won’t advance pay for 100s of dollars and only accept requests from inside the EU. As the paypal fees have gone up again lately, I’d prefer bank transfer for payment, which shouldn’t be a problem in the EU. Thanks to EU regulations, EU bank transfers don’t cost more than normal national transfers.

Cummulative group buy list as of Jan. 14th 2010 including the approximated chip prices in EUR according to the formulas above:

• 130x MBI5168 DIP16 –> 0.69€
• 115x MBI5168 SOP16-150 –> 0.69€
• 025x MBI5031 SOP24-300 –> 1.32€

ORDERED — Any news regarding the order will be posted in the comments section!

BTW, here are a few nice links: MathTeX, DeTeXify, No fake!

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