Last Week in Shenzhen

For the past two weeks I have been traveling in China, and I spent the entire last week in Shenzhen, the city known for electronics supplies, assembly and manufacturing, among many other things. I visited Shenzhen two years ago, and had an wonderful time there. On this trip my main missions are to visit a PCB assembly factory, check out a few pick and place machines (I am considering getting a second pick and place machine), to attend the Shenzhen Maker Faire, and above all, to have great food 🙂



Wells Electronic Technology Ltd.

Earlier this year I started working with Wells Electronic Technology Ltd. to get OpenSprinkler Pi and Expansion Board manufactured there. Wells is one of the numerous companies in Shenzhen that provides professional PCB manufacturing, assembly, testing, and packaging services. I’ve already done 3 orders with them. On this trip I wanted to pay a visit to check out their facilities in person. As a client, I was treated really well. They picked me up from my hotel, showed me around the factory, treated me lunch, and dropped me back to hotel. It was a very satisfying visit. The factory is divided into three sections. The first section is SMT assembly. They have 7 SMT assembly pipelines, each consisting of a stencil printer, pick and place machine, and reflow oven. Not all pipelines are occupied at all times, and the spare times are often used to accomodate small-size orders like mine.


There is also an X-Ray machine for examining the soldering quality of BGA chips. Fancy!

The second section of the factory is through-hole soldering. The workers first insert through-hole components into circuit boards, which are then sent to wave soldering machines. The third section is testing and packaging. There are literally no less than a hundred workers, all sitting in front of testing tables with testing instruments. It’s a pretty impressive scene.

At the end of the visit, I took a few pictures with my hosts Celia and Linna. They are both very friendly and hospitable. I was even given gift boxes of sticky rice dumplings, a traditional Chinese food to be consumed on the Dragon Boat Festival.


Revisiting Pick and Place Machines

About two years ago, I bought my first desktop pick and place machine — Neoden TM-240A. This is a decent quality budget machine that’s well-known in the maker community. It’s pretty easy to use and quite reliable. Although we use professional factories to make the OpenSprinkler line of products, for small circuit boards like SquareWear, ESPToy and RFToy, it’s still much more cost effective to make them ourselves. So it’s important to have a good and reliable pick and place machine in house. The major downside of TM-240A is the lack of a mechanical or vision centering system. This is one of the reasons it’s inexpensive. As we scale up, I am now on the market to shop for a new desktop machine with a automated centering system.

Before I went to Shenzhen, I contacted Felix at the LowPowerLab and got his recommendations for the DDM Novastar LE40V that he purchased recently. It’s a US-made high-quality desktop machine that provide both mechanical centering and vision centering. I even paid a visit to DDM Novastar in Philadelphia to check it out in person. The machine is quite impressive. My main concern is the cost — the total cost with feeders would be about $45K to 50K, which is quite steep. So I decided to wait till my Shenzhen trip to check out a few comparable China-made brands.

The first choice I have in mind is the Borey T15-F30 series. It’s a desktop machine with 4 headers and up to 30 8mm component slots. I had a chance to check out a sample machine at Borey’s Shenzhen office. To be honest, this machine is quite bulky, and given its size the 30-slot limit is a bit disappointing. The sales representative took quite a while to set up an initial demo, which made me concerned about the setup overhead. The machine including feeders would cost about $8K to 10K in total, which is a very decent price even after we factor in the shipping cost.

Borey T15-F30

The second choice is the new generation of Neoden’s pick and place machine. At the moment they are advertising their third-generation (TM-245P) machine. Since I’ve had two years of experience with TM-240A, I consider their machines to be well-built and fairly reliable, and their brand trustable. TM-245P is an upgrade to 240A with lots more component slots, mechanical centering, vibration feeder (suitable for components in tube packaging), and support for IC trays. The overall cost is about $6K to 7K.


During the conversations with their sale representatives, I learned that they will soon release the fourth generation with vision centering. This is a very interesting news that has come right in time. Vision centering is ultimately faster and more accurate than mechanical centering, so I’ve decided to wait for a couple of months for their fourth generation to become available. I’d like to get a sense of how it works before finalizing my decision.

Shenzhen Maker Faire 2015

I intentionally scheduled my trip to overlap with the Shenzhen Maker Faire 2015, which happened over the June 20 weekend. June 20 is also the Dragon Boat Festival, when we happily enjoyed the sticky rice dumplings of all sorts of flavors. The Chinese government has apparently decided to invest heavily in the make culture (a wise move!), and sponsored this event. As a result, it’s free to exhibit, free to attend, and even parking is free on site. The event was well organized with lots of makers. Compared to the Bay Area Maker Faire, it’s somewhat lacking in diversity, in that many exhibitions are of similar nature, and they are almost 100% for-profit companies/start-ups. I miss the days when the Maker Faire consists of mostly small but passionate makers who have the ‘I do it because I can’ spirit, not necessarily having profit-making as the primary focus. Let’s be honest, once it’s driven by profit, the focus is shifted to sales and marketing, and those are the kind of things I am neither good at nor very interested in. In any case, just my wishful thinking for future Maker Faire events.



Saturday (June 20) evening, I went to a social gathering organized by Hack A Day. Met some new friends and had a great time over there.


So ‘Good Bye, Shenzhen’ for now, but I hope to see you again soon!


We are at Bay Area Maker Faire 2015

Just a quick update: we are at the Bay Area Maker Faire 2015, station 2, booth 2542 (next to the game of drones). This year Samer is also joining me at the booth, so it’s gonna be great 🙂 We are demonstrating OpenSprinkler, OSPi, OSBo, OSBee Arduino shield, as well as SquareWear, RFToy, ESPToy, AASaver. In addition, we are debutting SquareWear WiFi — the new version of SquareWear powered by ESP8266 WiFi chip. Check out the quick 10 seconds demo below. If you are at the Maker Faire, come to check our our booth!


SquareWear WiFi LED Matrix Demo:

At Bay Area Maker Faire 2014

We are at the Bay Area Maker Faire at San Mateo Event Center. This year we got assigned to Station 5 (HomeGrown Village), which is a bit surprising because the past two years we’ve always been at Station 2 with the Arduino and Raspberry Pi gadgets. But this is probably an interesting change as we will be neighbors to other makers working on smart watering and home grown food. If you are at the faire, make sure to come by Station 5 and take a look at our gadgets. See you there!


The Story of OpenSprinkler: an Open-Source Web-Based Sprinkler Controller

Last week I wrote a short story on OpenSprinkler for the Make Magazine blog. It’s about how learning Arduino inspired me to invent the OpenSprinkler. Check out the blog post at the link below:

Thanks to everyone who helped and contributed to this project!

This year we will be having a booth at the Bay Area Maker Faire again. If you are going there too, make sure to drop by our booth and check out OpenSprinkler, SquareWear, AASaver, and the upcoming goodies. Thanks!

RI Mini Maker Faire Pictures

Yesterday we went to the RI Mini Maker Faire in Providence. I came back around midnight last night, feeling quite tired. It was a fun trip, and the first time that I went there as a maker. The faire was co-located with the Foo Fest, so even though its size is nowhere comparable to the Bay Area Maker Faire and New York Maker Faire, there were still a decent number of people. We had a single and fairly small table to showcase everything. As you can see from the pictures below, the table was very crowded, but we managed to lay out everything I wanted to show, and the promotional materials as well 🙂

As in previous Maker Faires, the most fun and rewarding part of the experience is that I get to talk to a lot of different people, explain to them how electronic gadgets work, get them excited about electronics, answer their questions, and hear their innovation ideas and solutions. I had two students, Kim and Cheni, who kindly offered their help, so I got to spend more time talking to people.



One tip I learned from the Bay Area Maker Faire earlier this year is that everyone is really excited about blinking LEDs. I know, it sounds trivial, but really, everyone loves it. Last time I just accidentally packed a hundred self-flashing and RGB color LEDs, together with coin batteries in my baggage. While setting up the table, an idea popped up in my mind that we can distribute them as free gifts at the faire. They are really cheap, so I don’t mind giving them away. What I didn’t foresee was how popular this was: the one hundred packets were gone almost in no time.

So this time, I am better prepared: I brought a bag of one thousand self-flashing and RGB color LEDs, together with one thousand batteries! We printed instructions so people can learn how to make an LED throwie on their own (basically sandwiching a coin battery in between the two legs of an LED). We distributed these as free gift to people, but told them it’s only free if they make one themselves (instead of taking away our demos 🙂 ) This was a huge success: I estimated that we gave away at least 250 of these. Many people passing by the table saw this and were eager to give it a try. Kids especially love these. Kim and Cheni were busy cutting tape and helping others learn to build their LED throwies. It’s really rewarding to see something so easy to learn can get people to excited, and it’s also fun to see how people were teaching each other at the table, and bringing their own friends to learn how to build these. Perhaps to some this will motivate them to explore the world of electronics. Then I will feel I have fulfilled my education mission a little bit 🙂


Heading to RI Mini Maker Faire Tomorrow

This is just a quick heads-up that we are heading to the RI Mini Maker Faire at Providence first thing tomorrow (Saturday) morning. If you are planning to visit the faire, make sure you drop by our booth to check out the latest gadgets, including the official OpenSprinkler v2.0s (with injection molded enclosure), OpenSprinkler Pi v1.2, all new AASaver 2.0 (blog post about this coming next), and the prototypes of OpenSprinkler Bee, OpenSprinkler Sip, and SquareWear 2.0. We will be selling physical products at the faire, and there is a small discount if you buy on site. Apologies for the lack of product updates recently, but more posts will follow after the Mini Maker Faier. Stay tuned!



2013 Bay Area Maker Faire Summary

First off, my apology for not updating the blog for a while. Right after the Bay Area Maker Faire on May 18 and 19, I went to a trip to the UK for about ten days. Then as I came back, I was faced with a load of orders that need to be processed immediately. My friend Don and I spent three days non-stop shipping out packages. Now that all the back orders have been processed, I finally felt relieved and can come back to take care of the blog.

As a quick summary of the 2013 Maker Faire: we had a great show. A big thumb-up to Aaron Newcomb for helping me out. Without him, I would not have made it to the Maker Faire. Lots of people came by, chatted with us, provided valuable comments and suggestions, and expressed appreciation and love 🙂 I took pictures with Chris Anderson, and Eben Upton and Liz Upton. I also met and chatted with Laen from OSH Park, Ian Lesnet from Dangerous Prototypes, Mark Frauenfelder (Editor-in-Chief of the Make Magazine), Jason Babler (Creative Director of Maker Media), Michael Caster from the Maker Shed, and many others. This is such a fantastic event, and a great opportunity to meet and make connections with other makers.


This year we didn’t bring many physical goods sell at the Maker Faire, but instead directed people to place orders online. This way we can devote more time to talk to people. Two interesting things I learned this year: First, AASaver is surprisingly popular and received much interest, but unfortunately I didn’t foresee this and hence did not prepare any new stock. What a pity! If I end up going to the New York Maker Faire later this year, I will make sure to take a batch of AASavers there. Second, kids really enjoy playing with flashing LEDs. We’ve set out a table with coin batteries and self-flashing LEDs, and provided simple instructions to make an LED throwie so people can make one right at the booth and take it away as a gift. This was hugely popular, and all the LEDs and batteries were consumed in no time. Apparently I should prepare more of these next time!

Of course the primary focus of the audience at our booth is on OpenSprinkler and OpenSprinkler Pi (OSPi). Since the release of OSPi just a couple of months ago, it has started gaining significant interest and has become the fastest growing product on my site. So far there have been more than 350 OpenSprinkler Pis out there in the wild. And as you can see from the forum, lots of people have been keenly working on developing their own software, using different programming languages and implementing advanced features such as weather-based control and sensor-based control. As I will talk about in the next post, the same firmware that’s running on the microcontroller-based OpenSprinkler has now been ported to OSPi, thanks to the generous contribution by Kimberling. So now you can run the same full-featured interval program on OSPi as in the standard OpenSprinkler.

But if you think the microcontroller-based OpenSprinkler is losing its charm, you couldn’t be more wrong 🙂 Although not growing as fast as OSPi, it’s still selling extremely well. Anyone who recently ordered the assembled OpenSprinkler has probably found out that we’ve been `secretly’ upgrading your order to a pre-release version of OpenSprinkler 2.0. As I will talk about in a follow-up post, OpenSprinkler 2.0 has an upgraded mcu (ATmega644), microSD card slot, the ability of adjusting LCD backlight brightness and contrast, more available pins to interface with external sensors and actuators, and pin headers to directly plug in an RF transmitter in order to interface with remote devices. The only difference of the pre-release version with the final version of 2.0 is in the enclosure design: the pre-release uses the current enclosure, and the final version (which is in production at SeeedStudio) will be using the new injection molded enclosure. There are many good reasons to prefer the microcontroller-based OpenSprinkler over OSPi: it is pre-flashed and works out of the box, so no hassle with installing raspbian, doing ssh, or dealing with Linux; it has LCD, buttons, and a number of analog pins to interface with external sensors; also I personally really like microcontrollers because of their simplicity and the fact that the controller is instant on when you need to restart it.

Uhh, I think my thoughts are already drifting away from the Maker Fairem which is supposed to be the focus of this post. So let me conclude this post here, and more exciting posts about recent updates will follow next!

Preparing for Bay Area Maker Faire 2013

Contrary to what I mentioned in a previous post, I have made the very last-minute decision to attend the Bay Area Maker Faire 2013. I will be flying out of Massachusetts early tomorrow morning, and get to the Maker Faire ground in the afternoon to do initial setup. Aaron Newcomb has kindly volunteered to help me at the booth. If you are planning to come to the Maker Faire, be sure to drop by our booth (exhibit 3375, Expo Hall with commercial makers), and watch our demos.

We will be showing most products I’ve developed so far: OpenSprinkler (including DIY 1.42u, the new assembled OpenSprinkler 2.0, and new injection molded enclosure), OpenSprinkler Pi, SquareWear (with lots of pictures of wearable electronics workshops I’ve hosted int he past, and SquareWear demos), AASaver (including the upcoming AASaver 2.0 I just blogged about earlier tonight). So it will be quite a show!

It has been fun to prepare the demos, and a lot of work too. Below are my sketches for two of the OpenSprinkler demos:

and some real gears to go with the two demos:


In terms of promotional materials, new this year I have made a banner and some business cards to be distributed at the table:

These were made in the last minute, so they are not as professionally looking as I wanted, but the essential information is there 🙂 Also, I will have lots of colorful info pages and pictures at the table.

Time to go to sleep and prepare for the trip tomorrow. Hope to see you at the Maker Faire OpenSprinkler booth!