PART 2, SCREAMING CIRCUITS AND THE MAKER COMMUNITY

My last post mused on the affordability of assembly at Screaming Circuits for the maker/very small business/kickstarter community. My hypothetical Arduino-compatible dual motor driver Kickstarter came out to $9.81 per board at a quantity of 250. That's probably more than a cheap off-shore assembler, but we'll get you 100% yield. They probably won't.

TI TPS62601 front and backIt's more than just cost though. Many of the budget manufacturers won't do the most complex parts. For example, I could shave about a square inch off of the board size - maybe two - by using 0402 or 0201 passive parts. That's about $.50 - $.75 less per board for the blank PC board. Most discount assembly shops won't assemble 0201 parts. Many won't assemble 0402 parts. Screaming Circuits will assemble 0201s, and your little micro BGAs too!

The part on the right is a tiny wafer scale BGA next to the edge of a U.S. dime. We can build that.

If you're just designing the board and not hand assembling, putting in 0402 or 0201 parts is no big deal. You just design it and let the robots build it. If your assembly house can't deal with those small parts, your stuck. You've lost some freedom of choice.

Now, you would expect me to be biased, because I work here, but more than bias, it's a matter of picking the right tool for the job.

If time is your key driver and cost isn't an issue, you'd want quick-turn Full-Proto; our Short-Run production would be the wrong tool.

If cost is your key driver, you have more time, you need predictability, and need good yields, our 24 hour Full-Proto service might bankrupt you, but our 20 day Short-Run can do all of the hard work for you, and you'd know exactly what you're getting, and when: 250 working boards in 20 days, for a decent price.

Here's a Kickstarter project we built earlier this year.

Duane Benson
Don't use a Marten64 0-dot-19 Freembulator when you really need a Model B Mitchel Warbler brand size 32.125 green Sackcombobulator.

 

Part 1, Screaming Circuits and the Maker community

Can Screaming Circuits, a full-service assembly provider, compete with a “no-frills” assembly house?

Upon first thought, it might seem like Screaming Circuits, would be too expensive for anything but well-funded big-business and big-education. In reality, that may not at all be the case. Like so many other things in life, there are trade-offs between time, effort, and money. The nice thing about Screaming Circuits is that, unlike the low-cost small volume manufacturers, we can cover both ends of the spectrum.

Our least expensive service is not as cheap as the lowest-cost assemblers. We don’t sell on price, but when you start to add in reality and practicality, the cost difference gets much smaller.

OpenHardware logoIf you need that maximum performance, “I need it now, now, now!” service, there’s no question that you need a premium manufacturer, like Screaming Circuits. But let’s do some compare and contrast on the other end of the spectrum. Can Screaming Circuits be a good deal for a maker?

I’ve got an open source Arduino-compatible robot motor board that I designed a while back. I’ve hand-built a few, because I enjoy soldering, but for this exercise, we’ll pretend I’m a maker with a Kickstarter and I need more built up.

I’ll need 250 for the hypothetical Kickstarter project. The 1.5” x 3.5" board uses an ATMEGA32U4 processor with the Arduino Leonardo bootloader. From a software perspective, it looks just like a Leonardo. It uses a different hardware form-factor than the standard Arduino to better fit a mobile robot.

1-DSC_0001It’s got 26 different components (26 line items in the Bill of Materials). Due to some part types being used in multiple places, that’s a total of 48 surface mount (SMT) placements. I’ll ignore the few thru-hole parts. As a Kickstarter, I would supply the board with all of the SMT parts installed and let the customer solder in the thru-hole parts. That’s pretty common practice in the hobby, maker and Open Source world.

You can quote the assembly on the Screaming Circuits website without registering, so let’s do just that. It’s got:

  • 250 desired board quantity
  • 26 unique parts (BOM line items)
  • SMT on 2 sides? Yes
  • Lead-Free? No (If you’re shipping into Europe, you’ll need lead-free)
  • Class III? No
  • ITAR? No
  • 48 SMT parts
  • 0 thru-hole
  • 0 BGA/QFN

For 20 day, Short-Run production service, this comes out to $9.81 per board - less than $10.00 each.

Soldering by hand, I can do about two an hour. Some folks are faster than me, but some are slower. At two per hour, I’d spend 12 ten-hour days hand soldering the 250 boards. Ouch!

You can most likely find a cheap overseas manufacturer that would build 250 them for less, but they may not want such a small job. You may end up with concerns about intellectual property theft, and you may not get the yields you need.

At Screaming Circuits, we treat every job as proprietary, we’re happy with a run of 250 without any commitments for more, and we promise 100% assembly yield. Finally, a job like this, that totals out to $2,452.48, gets the same process and care as does a $10,000 quick-turn complex prototype.

Food for thought.

Duane Benson
Here's a Kickstarter we built back in 2012

The Value of Open Source

There were a number of interesting sessions and debates last week at the DesignWest show. One of the more passion filled, was on the value of Open Source hardware. Some people think it will save the world,if only everyone will do everything open source. Some people think it's a stupid waste of time without a real business model.

Personally, I see more value in it than either of those extremes. What I see is that open source hardware (and software) has lowered the barriers to entry for people who want to create, design, build and sell. Yes, big companies innovate, but a vast amount of innovation and employment comes from small companies that start out without anything more than ideas.

A decade ago, before open source hardware became well know, it was pretty difficult and expensive to start a hardware company. In fact, I recall quite a few predictions and discussions about the death of hardware as an industry in the country. Open source hardware has lowered the barriers to entry and raised the level of awareness of hardware to the point that now, in my opinion, the environment is as ripe for start-up companies and innovation as was the late 1970's and 1980's.

Open source hardware has given us that, and that will be far more positively economically impactfull than whether or not an specific business can find a way to make money with open source hardware. These new businesses may or may not sell open source hardware. Again, that's far less important than the fact that open source hardware has really enabled so many more people to create.

Particle Update

I've been ignoring my Geiger counter for a while now, but I picked it back up and made some progress again. For some reason, I just wasn't getting the 555 based HV power supply to generate a high enough voltage. In frustration, I bypassed the 555 and fed a PWM signal in from a microcontroller board that PIC SMT geigerI have laying around.

That fixed the problem. I still don't know why I wasn't able to the the 555 doing what it was supposed to do. I'll have to spend some more time on that some other day, but for now, I've prototyped it out and I'm happily detecting particles. I whipped out the new layout and will send off to Sunstone.com com for another set of PCBs.

I've also replaced the Atmel chip with a PIC. I don't have anything against Atmel. I'm just more familiar with PICs. Once I've built a few of these, I'll change to really small packages - QFNs or BGAs for the chips - to make the board a little more fitting with our assembly capabilities. The SOIC chips are fine, but our machines don't even come close to breaking a sweat with things that big.

Duane Benson
We treat agoraphobia for PC boards

Thru-hole to SMT

Thanks to a comment from Michael yesterday, I think everything is now cool with my Geiger counter. I had left the AT2313 default fuse setting at clock/8. That dropped the RS232 speed from 9600 to 1200 and it made the clicking sound into more of a tone, which just didn't sound right for a geiger counter. I still need a good radiation source though. I think I've picked up just a few clicks of background radiation, but that could just be wishful thinking.

WishfDFN-8ul thinking or not, that's not the point. The point is that this was an example of migrating from thru-hole parts to SMT. I managed to get virtually everything into SMT. The connectors, the power switch, the buzzer, batter holder and fuse clips for the tube stayed thru-hole. Although I'm sure I could have all but the battery holder and fuse clips into SMT had I wanted to. I tend to keep switches and connectors that will get a lot of use as thru-hole just for the extra staying power. If they aren't used frequently, then SMT is just fine.

There are a number of things to consider when switching from thru-hole to SMT:

  1. Everything is smaller, so you can fit more in the same space or the same in less space. I took advantage of the extra board area to add in a RS232 line driver so I could connect directly to a serial port. I also added in a power-on LED.
  2. Everything is smaller so your layout is more critical. Most PCB houses will build 8mil trace and space as standard process these days. That gives you a lot of flexibility in squeezing your routing into tight areas, but it doesn't give complete freedom. You have to be core careful because you frequently do have to route a bunch of traces into a pretty small area. When you get into the really fine pitch parts, like .5 or .4 mm center to center, you have to be extra careful.
  3. Some parts are dimensioned in metric and some in SAE units. If all are one way or the other, it's easy. But when you've got both, you may have to tweak with your grid spacing off and on to make sure your traces are centered in the SMT pads they connect to. It usually isn't a horrible problem, but it can make even spacing more difficult and can make you more likely to violate a design rule.
  4. You don't have automatic "vias" on each component leg so routing can be more difficult. You'll likely have to spend more time tweaking the part locations and the trace routing to get a decent layout. A lot of times everything's too close so it's not practical to just plant a lot of vias all over.
  5. Hand soldering is less or not practical. Some people do hand solder some pretty tiny parts, but it's not practical in more than isolated cases. If you're a hobbyist or on a tight budget, this might limit you to thru-hole or some of the largest SMT parts. For commercial work though, SMT is the way to go.

Some things to think about. But what do you get in return? Typically lower cost - especially if you want your design to go into volume manufacturing. You also get access to the newest parts that only come in SMT packages. And, many designs are space constrained, so you can cram more in while still keeping your board size down.

Duane Benson
I shot a neutrino into the air
And where it landed I already knew

 

Geiger Counter without the Muller?

My Geiger counter project has been on holiday for a while. When I originally ordered all of the parts, I ordered fuse clips (to hold the tube) with solder lugs too big to fit in the holes and a trim pot (VR1) too small for the SMT pads. I moved on to other things for a while and just now got around to ordering the correct parts and soldering them in. I've verified that everything works except the tube. Apparently, S-13BG GM tubethe specific tube I bought (SI-3BG) is not very sensitive.

Other than not knowing if it will actually detect radiation, everything seems to work just five with Mighty Ohm's original Atmel code. The only difference from his instructions is that the RS232 is 1200 baud instead of 9600. I'm not entirely sure why that is. The source code specifies 9600 and I have an 8MHz resonator just like his kit. I'll worry about that later. At least it works.

It will beep if I touch my fingers to each lug of the geiger tube, but I haven't been able to detect any naturally occurring particles. There are a couple of possibilities.

  • I had to choose a different transistor for Q1 and different diode for D1 because I couldn't find those specific parts in SMT. Maybe the gain or some other performance spec is too far off.
  • The type of tube I bought is not sensitive enough so I just need to find a stronger radiation source.
  • I don't have VR1 set right to give a high enough voltage to trigger the tube.

I'm going to try a 100:1 voltage divider to a unity gain current amp to measure the voltage and go on the hunt for a hotter (but still safe - I hope) radiation source. I might go back to eBay and buy a different tube too. Lastly, I'm going to get out some data sheets and look at my subs again. Maybe try to find something even closer to the original. Once I've verified that it all works, I'll make the design files available as open source.

Duane Benson
If the Alpha is the tough guy, why can it be stopped by a single sheet of paper?

Open Source. What is it Good For?

I've written about open source hardware (OSHW) a few times before. Like this and this. I've understood open source software for quite some time and over the last few years have been starting to get what open source hardware is all about. It is different than open source software.

With software, your tangible product is essentially intangible. Your acquisition and distribution of an open source project can be virtually free. Not so with hardware. Someone has to physically build something, which costs time and money in parts and labor. Really though, all that means is the proliferation of an open source hardware product just takes a little longer. If you look at it as the design being open source more than the actual product, then it gets to be more and more similar to software.

While open source software has moved into real business, hardware is still more closely associated with the hobbyist community. That is changing though. Ti's Beagleboard is serious stuff from a serious company. Some of the hobbyist catering OSHW companies are growing to or have grown to the point of being serious businesses (Adafruit, Sparkfun).

This all begs the question: "What is open source hardware good for?" Let's divide and conquer. Or, at least, divide and explain.

  • What does it do for innovation?

History is rife with stories of great inventions that were not commercially successful because the inventor was a good inventor but was a lousy business person, didn't have access to funding or just didn't have the drive to build, promote and sell the product.

With OSHW, companies that do have the drive, funding and know-how can pick up an open source project from a developer that doesn't.  There are none of the IP concerns that sometimes keep big companies from taking on product from independent inventors. Great products that otherwise would stay hidden can make it out in the world.

Some OSHW companies, like Adafruit compensate the designers who's product they sell. No marketing or selling expense for the designer and yet money comes in to them. Much reduced design expense for the seller, yet they can build a business.

  • What does it do for small companies?

It's another way to jump-start design or production of products that will fund the small business. It can reduce the barriers to entry. People who are good at designing but not so good at selling can still earn money. People who are not so good at designing but good at selling can earn a living. People who are good at both designing and selling - they have the best of both worlds and can earn a living. Products that would otherwise stay in obscurity can more easily make it to the world.

  • What can it do for big companies?

The answer to this question has been the longest in coming, but there are more and more answers showing up. Take the Beagleboard from Texas Instruments. It got a new processor (the OMAP) out into the hands of their customers quickly. It was a great promotional tool. The software side of an organization could get started with the processor without having to wait for the hardware folks to design, layout and build the hardware. The hardware folks could see how the part and its accessories work in real life.

OMAP users could get a jump-start on complex tasks like escape routing. The manufacturing folks could get some insight and practice into assembling the package on package processor / memory combination. design cycles are short enough as it is. Companies that want to use the Ti processor get professionally designed short-cuts. Ti gets to sell more processors quicker. Everyone wins.

Duane Benson
It doesn't mean destruction

IS IT VALUE? IS IT PROTO?

SMT Geiger PCB

Looks like it to me. I got a couple of nice PCBs from Sunstone here. The parts, except for the Geiger tubes are here from Digi-Key too. The tubes are someplace between the Ukraine and Canby. All I have left to do is kit it up and place the order here at Screaming Circuits. It may seem silly that I have to go through the effort of placing an order on our web site when I work here. But it's not.

Doing so does two things. It reminds me of what it's like to be a customer. Always a good thing. And, it doesn't disrupt the shop floor with something that is outside of our process.

In case you haven't been following, this is my SMT re-layout of the open source Geiger counter designed by Jeff Keyzer of MightyOhm.com.

Duane Benson
Tick. Tick. Tick. Tick. Tick. (actually, I hope not)

More Geigering

SMT Geiger 2nd I didn't get back to this at the same bat channel and same bat time. Sorry if anyone tuned in and found the Penguin instead. I think I'm ready now though. I did a bit more layout tweaking, moved the MCU bypass cap closer to the supply pins and added in a MAX3232 so that I won't need an external driver / transceiver board if I want data on my PC.

I'm calling it done. I have my gerbers in a .ZIP file, my centroid and the completed BOM . Next step is to get some PCBs fabbed up. I'm trying out the ValueProto service from our partner, Sunstone Circuits. As I said before, if, after assembly, this design actually works and counts Geigers, I'll post all of the design files as needs to be done with Open Source hardware.

Here we are at ValueProto. The PCB is 4" x 2.7". I'm not going to do a quick build and my zip is 97013. $57.40 for one. $34.90 each in quantity ten. That's all the questions I need to answer. I upload my .ZIP file, check a few boxes and the order is now placed. Next, I'll get some parts, kit it up and send it through Screaming Circuits. The NOS Soviet Geiger Mueller tube is one the way from the Ukraine.

I'm not sure what I'll use as a radiation source to test it out with once it's built. I hadn't really thought that far ahead. I'll have to come up with something.

If you're going to be at the Embedded Systems Conference in Boston next month (September 27, 28), we'll be there in booth 615, across the isle from Element14. Stop in and take a look at it. While you're there, ask for fabulous prizes and gifts. We have a smattering of Screaming Circuits shirts and flashlights for the asking.

Duane Benson
No baked beans, please

Open Source The Eskimo

Not long ago, I found myself in the vicinity of the former Trojan Nuclear Power Plant. I say former, because it's not there anymore. The reactor's long gone and the cooling tower was exploded a few years back. I was just under a mile away, and downwind, from the tower when it went down. The cooling tower didn't have exposure to radioactive material when it was in operation, but the dust cloud was still pretty annoying. Interestingly, prior to the nuclear power plant being there, the land was owned by the Trojan Powder Company, maker of explosives. I wonder if the blasting material was made by the Trojan Powder Company. Today, there's just a park and a few abandoned buildings left on the spot.

While I was there recently I pondered the possibility of small amounts of residual radiation in the area. I quickly forgot the thought until I ran across a post by Jeff Keyzer (mightyohm.com) about an open source geiger counter he designed.

SMT Geiger Well, who could resist the chance to build a geiger counter and run it around looking for bad stuff at the former sight of a nuclear power plant. Not me. Here at Screaming Circuits, we specialize in surface mount, so I thought it would make sense to re-layout the PCB for SMT components. Which I did. That's the cool thing about open source. (one of the cool things) The design files are accessible.

The only real challenge I had was in finding a few parts substitutions. The exact match wasn't available in SMT for some of the components. Hopefully, I picked good subs. Doing that is frequently not as easy as it might seem. Especially when the original design is not mine so I don't necessarily know which parameters are in the criticle path.

Now I have to get some parts from DigiKey or Element14, PCBs from Sunstone Circuits and I'll have to run over to Eastern Europe to pick up an old Soviet era geiger muller tube. If my layout actually works, I'll pack up the SMT files and BOM and make them available as all open source is supposed to be. If it doesn't work, I'll quietly try to disavow any knowledge of every having tried to mess with it.

Duane Benson
Everybody's building ships and boats
Except us. We're building prototypes.