Tagpcbs

Smart-Prototyping.com Review

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Recently, Matseng at the Dangerous Prototypes forums posted another source for cheap printed circuit boards and test equipment direct from China:

http://www.smart-prototyping.com

The site is apparently run by German ex-pats in Shenzhen.  Although the site is pretty sparse at the moment, they’ve got a PCB prototyping service and a selection of very cheap test equipment for sale.  I placed an order for some PCBs and a Bench Supply on the day the Chinese New Year ended.  They arrived Thursday.

PS-303DM Power Supply

The bench supply looks great.  I tested it with a crappy RadioShack meter and some resistors, and the readout is at least as accurate as the meter.  This is every bit as nice as power supplies 3 times as expensive.  When I received it, the switch on the back was set to 220v, and contrary to the description, it did not come with a power cord, but for the cost, I’m very, very happy.

Smart Prototyping Circuit Board

The PCBs also came out very nicely.  These are nothing particularly taxing (these board are for a possible through-hole kit to sell on Tindie), but the drill hits are every bit as accurate (if not better) than Seeed Studio or iTead studio.

Overall, I’m very happy.  The service was really quick (less than 2 weeks!), and the price was good.  Shipping was on the high side, but considering the price of the power supply, nothing to complain about.

 

Nanino Upgrade

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4 months ago, I read about Johan’s Nanino on Hack-A-Day, and thought it would be a great way to teach some folks how to etch their own circuit boards.  Although I’m increasingly shipping PCBs off to China, being able to etch your own boards is a valuable skill to have.  I’ve taught workshops on it in the past, and I’ve described the process on this blog.  Today, I set out to make a copy of Johan’s Nanino, but was almost immediately frustrated by the inability to manipulate and print the board file in a way that worked well for my process.  In the end, I redrew the thing using DipTrace.

Nanino ImprovedThe only change made to the original is the addition of a .1 uF capacitor on the DTR line of the FTDI header.  Some of the traces are a little closer together, but they’re still spaced out enough that etching this board is a cinch.

Here are the files:

Diptrace Schematic for Nanino

Diptrace PCB for Nanino

PDF of Nanino from the Back

You can use this PDF to etch directly.  No mirroring is needed.

Can be printed.  1200 DPI.
Can be printed. 1200 DPI.
Can be printed. 1200 DPI.  No mirror needed for etching.
Can be printed. 1200 DPI. No mirror needed for etching.

DXF of Nanino

And, because the original Nanino is licensed CC-BY-NC-SA, this one is also:
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

 

It works!
It works!
Good toner transfer
Good toner transfer
The etch was drama-free
The etch was drama-free

Cheap Prototype PCB Comparison

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We live in a golden era of the electronics hobby.  PCBs are easier to make and cheaper to manufacture than ever before.  In some cases, it can even be easier to have  PCB made than breadboard a circuit.  With the growing proliferation of surface mount components, and ever greater levels of integration, PCBs are more and more appealing for hobbyists.  Like most folks in the maker community, I get my PCBs made at one of three places: Seeed Studio, OSH Park, or Batch PCB. (Itead Studio, also, but their prices and quality are basically the same as Seeed Studio.)

I’ve been ordering from whatever place strikes my fancy at the moment (increasingly from OSH Park, so I’m not left waiting as long for the boards), but I’ve never seen a decent comparison.  A few minutes in Octave fixed that right up.  Without further adieu, the price of 10 PCBs from OSH Park, Seeed Studio, and Batch PCB.  In order to compare apples to oranges, I assumed expedited shipping for the Seeed Studio orders.  In practice, this means about 10 day turnaround time for all three options.  All board dimensions are in CM.

 

Pricing for Expedited PCBs from Seeed Studio. X and Y are board dimensions in CM, Z is cost in US Dollars.
Pricing for PCBs from OSH Park. X and Y are board dimensions in CM, Z is cost in US Dollars.
Pricing for PCBs from Batch PCB. X and Y are board dimensions in CM, Z is cost in US Dollars.

This view gets even more interesting when you plot all three on the same graph:

The Mountain Range View of PCB Costs.

The stair-step pattern is Seeed Studio, the middle-surface is OSH Park, and the top surface is BatchPCB.  So, for 10 PCBs in about 10 days, OSH Park is the cheapest up to about 20 cm^2, then Seeed Studio is cheaper.  Here’s a heat-map of that price-breakdown.

Best Cost for 10 PCBs in 10 days. Yellow is OSH Park, Green is Seeed Studio. X and Y are board dimensions in CM.

 

Of course, sometimes you don’t need 10 boards.  In this case, OSH Park is the winner in a lot more cases.  In that case, here is the cost breakdown:

Best cost for minimum number of PCBs. Yellow is OSH Park, Green is Seeed Studio. X and Y are board dimensions in CM.

And, of course, sometimes you don’t care when the boards arrive.  If you don’t mind waiting for 3-4 weeks, here’s where you’ll find a better deal:

Best Price for PCBs, no rush. For Seeed, this means 4 weeks or so. For OSH Park, this means 10 days. Yellow is OSH Park, Green is Seeed Studio, X and Y are board dimensions in CM.

So, here’s the verdict:  Never order from BatchPCB! (Sorry Sparkfun.)  Otherwise, figure out whether you need a lot of boards, board fast, or boards slow.  Depending on those answers, look at the heat maps above, and find your best deals!