# Macroblock LED driver group buy

I’ll be placing an order at Kingelectronics on January 14th 2010.

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:

• $p_{i}:$ price of a single chip in US$as per Kingelectronic’s website. • $p_{i}^{\prime}:$ price of the chip in € including all import costs that I have to pay. • $S_{imp.}:$ shipping costs for importing the whole order (current estimate: 30$).
• $S_{EU}:$ shipping cost from Me to You in € (somewhere between 1.45€ and 3.00€).
• $H:$1€ handling. carton, envelope, tape etc.
• $N_{i}:$ number of parts for a certain component (i) (whole order).
• $N_{i}^{\prime}:$ number of parts for a certain component (i) (yours only)
• $T_{imp.}:$ import tax in % that I have to pay for the whole order (parts + shipping, 19%)
• $n:$ number of different components
• $i:$ component (i)
• $C_{cnv.}:$ €/$ratio on January 14th 2010 • $P_{user}:$ price in € for your parts including shipping from Me to You. $\dpi{150}p_{i}^{\prime}=\Bigl(p_{i}+S_{imp.}\cdot\frac{p_{i}}{\sum\limits_{i=1}^{n}N_{i}p_{i}}\Bigr)\cdot{C_{cnv.}}\cdot(1+\frac{T_{imp.}}{100})$ $\dpi{150}\displaystyleP_{user}=\sum\limits_{i}N_{i}^{\prime}p_{i}^{\prime}+S_{EU}+H$ So the chip price $p_{i}^{\prime}$ 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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### 25 Responses to Macroblock LED driver group buy

1. Helmut says:

Es ist schon verblueffend, wie verwirrend man die einfachsten
Sachverhalte darstellen kann. :-)

2. robert says:

Das ist aber eindeutig.

Wenn das ein Beamter oder Rechtsgelehrter in Textform haette schreiben sollen, waeren das bestimmt einige DIN A4 Seiten geworden.

3. Helmut says:

Du redest zuerst von 50$dann von 30$ und zum Schluss von 60$. Das werwirrt. Solange deine Kunden nicht wissen wie gross die Sammelbestellung wird, sind fuer sie die Endpreise ein Vabanquespiel. 4. robert says: Die gegenwaertige Anzahl der Chips die bestellt wird ist in der Liste ausgewiesen, somit ist alles eindeutig berechenbar. Und wenn du Versandkosten und Materialpreise nicht auseinanderhalten kannst… Die von dir monierten Werte kommen aus einer Textpassage, welche mit “Example” ueberschrieben ist, und das bedeutet noch immer Beispiel. Simple Algebra muss ich schon voraussetzen koennen. 5. Helmut says: Und Englisch. :-) 6. Martijn says: I’m willing to participate and buy 10, which would bring the total to 100 and costprice to$0.50 a piece. I’m inside the EU ;)

7. robert says:

Hey,

did you put the numbers into the formula, or where did you take the 50¢ from the “example” ?

8. Martijn says:

Heh, I took that from the example and missed the ‘0.90€’ bit.
That price is still pretty good though, considering I can’t get the chip locally. So, I’m still in :)

9. robert says:

OK. I’ll update the list.

10. Martijn says:

Martijn :
I’m willing to participate and buy 10

On second thoughts, make that 12, please.
That way I can drive 4 8×8 matrices if I ever want to.

11. Martijn says:

Martijn :
I’m willing to participate and buy 10, which would bring the total to 100 and costprice to $0.50 a piece. I’m inside the EU ;) On second thoughts: make that 12, please. That way I can drive 4 matrices, if and when needed. 12. robert says: OK. 13. Jan says: Moin, ich wuerde gerne auch noch ein paar Chips mitbestellen, wenn es moeglich ist: 5x MBI5168 DIP16 5x MBI5168 SOP16-150 5x MBI5031 SOP24-300 Vielen Dank! 14. robert says: OK folks, I’ve just placed the order at kingelectronics. The shipping costs were 30$ and have been incorporated into the chip prices using the formulas I’ve posted. If I should here from them, I’ll post the news in the comments. Once the stuff arrives (may take a while), I’ll be needing your shipping addresses as well.

15. robert says:

I’ve just got a reply from kingelectronics. They need to restock, so it will take some time until delivery. Maybe 2-3 weeks.

16. robert says:

No delivery yet. The money has been withdrawn from my credit card, therefore our order is still being processed right now.

17. Jan says:

Hi,
I felt sorry for not checking earlier, but it has been quite a busy time lately. Just drop me a Mail when you want that money and the address for the delivery.
Thanks (oh, deutsch waer auch gegangen ;)

18. robert says:

I’ve sent an email to Kingelectronics.com asking for a status update. When the order was placed, they only spoke of a 1-2 week restocking delay, not 4 weeks. As I haven’t received a shipping notification, I guess they’re still trying to get the parts… Maybe the Chinese new year’s celebrations are interfering. They should be over by February 20th or so.

19. robert says:

Currently they expect to get new parts shipped to them by Friday. If that actually happens, will have to be seen. I’ll get an update tomorrow.

20. robert says:

OK. Chinese new year’s celebrations have delayed it. New date is roughly end of February :-(

21. Martijn says:

patience

must… have… it….

Silver lining: February is only 28 days ;)

22. robert says:

Yeah, well…

Today I’ve sent the next email asking where the “beef” is.

23. robert says:

Drum roll…

I’ve just been told, we’d get a tracking number by tomorrow.

24. robert says:

…apparently not :-(

Seems like I should investigate how I could get my money back, just in case this little project goes belly up.

25. robert says:

FINALLY!

The chips have arrived, well packed in anti static shielding bags. If you haven’t done so already, please send me your shipping addresses. I’m doing the math right now.