Science Projects

[Andrew] was getting some poor performance from a couple of USB devices he had connected through an unpowered hub. This is a problem because the hub prevents devices from negotiating with the host controller for more current. He fixed it by adding an external power supply to his USB hub. In this case the PCB already had a footprint for a power connector. The manufacturer uses one board for several different models and just leaves the supply components unpopulated. [Andrew] managed to find a barrel jack in his parts bin that matched the footprint. One important thing to do before hooking up the source is to disconnect the 5v wire from the incoming cable from the computer. The other tip we can give you is to use a good regulated 5v source to ensure you don’t damage the stuff you’re trying to power. That means avoiding deals that are too good to be true. Filed under: peripherals hacks

“miceuz” have set up this little experiment to gain a better understanding how does a SAR analog to digital converter work. Go to http://wemakethings.net/2013/02/25/how-does-adc-work/… for more info and Arduino code. How does an ADC work? - [Link]

What’s inside the JBC CD-2BB soldering station - [Link]

When work on an engine control circuit [Scott] found himself in need of a way to compare the performance of two control circuits at once. The hobby quality oscilloscope he owns wasn’t up to the task. After thinking about it for a bit he ended up using his ears as the oscilloscope. The signals he was measuring are well suited for the challenge as they fell within the human range of hearing. He used some wire wrapped around each of the three conductors on the jack of his headphones in order to connect them to a breadboard. Then he simply connected each channel to one of the motor driver circuits, and connected the common ground. Listening to the intonation of the pitches in each ear he was literally able to tune them up. If he had been looking for a specific frequency he could have used his sound card to take and analyze a sample. But balance was what he needed here and you must admit that this was an easy and clever way to get it! Filed under: digital audio hacks, tool hacks

The weekly – SHOW AND TELL is on the Adafruit Industries Google+ page! at 9:30pm ET We will be asking all the folks in the +Limor Fried (ladyada) show-and-tell circle to re-add themselves to the +Adafruit show-and-tell circle shortly. Please post a comment on the Adafruit page to be added! Make sure you add Adafruit to your circles first!

ASK AN ENGINEER – 10PM ET! SATURDAY 5/25/2013! What is “Ask an engineer”? From the electronics enthusiast to the professional community – “Ask an Engineer” has a little bit of everything for everyone. If you’re a beginner, or a seasoned engineer – stop in and see what we’re up to! We have demos of projects and products we’re working on, we answer your engineering and electronics questions and we have a trivia question + give away each week. Previous chats can be viewed at http://www.adafruit.com/ask Chat details! Visit our new “Ask an Engineer”section on Adafruit at 10pm ET, Saturday nights Or visit our Ustream page For old schoolers, you can use IRC, you’ll need a Ustream log/pass, check out the Ustream IRC how-to here We are #adafruit-industries6796 on IRC server chat1.ustream.tv Watch the show with an iPad, iPhone or Android phone! And don’t forget, 30 minutes before the show we’re doing our weekly show-and-tell. If you are on Google+ and want to join, just add/follow +Adafruit’s page and post a comment so you can be added to the show and tell circle. At 9:30pm ET you will see a link to the hang out. Just keep your mics muted until we call on you and have your project ready. For those who just want to watch, you’ll be able to watch it live on Ustream here and we usually have a recorded version posted later.

I cut my losses and tossed the hose and the sprayer.

The Half-Ohm is a very nice and small adapter that plugs right into your DMM. The Half-Ohm is made by Jaanus Kalde and you can get it here. It does NOT come with a battery, so make sure you have … Continue reading →

Hi, dear friends, from the date of establishment, ElecFreaks has released a wide range of products,  and fortunately attained substantial attention and support , meanwhile, we also received lots of emails seeking for technical support from hobbyists all over the world. So we undertake to enrich our tutorials in diversified...

CO2 Soldering Reflow soldering in toaster oven or on a skillet is popular among hobbyists and small-scale manufacturers. The process is simple and the equipment necessary is inexpensive and readily available. The results are very good if several simple rules are followed. One of these rules is to use freshly made PCBs – the shelf life of hot air leveled tin PCB finish is 6 months. A PCB which was used close to the end or past its shelf life will exhibit poor solder wetting resulting in bad joints. Poor wetting can be overcome by increasing soak time and/or rising reflow temperature to give solder flux more time to act on oxide layer formed on the PCB finish during storage and reflow. This approach worked well in good old times of leaded solder, however, modern lead free solder reflow temperature is already quite high and increasing it may not be possible. In this case, soldering in inert atmosphere could be better option. In this article I will explain the process that I have started using some time ago – with great success. Conceptually, soldering in inert atmosphere is easy: substituting air (which contains oxygen) in the oven with inert gas eliminates the cause of oxidation. The best gas for this purpose is nitrogen; it is non-reactive at soldering temperatures and being the major component of air it is the cheapest of all industrial gases. Being air-like it is also easy to use – all that is needed is a constant low volume flow into the oven during soldering cycle. Nitrogen is available in several forms, the most suitable for soldering applications is compressed in a cylinder. Additionally, a regulator is needed to drop down high cylinder pressure. The price for the set starts at about $150. The cylinder can be refilled in places like Airgas for about $10. Another gas suitable for creating inert environment is carbon dioxide or CO2. Unlike nitrogen, this gas has household uses. It is widely used to fertilize planted aquariums, carbonize beer, grow plants and several other things. Since I already own CO2 cylinders and regulators my reflow process uses this gas to create inert atmosphere. For volumes I use the difference in nitrogen/CO2 refill prices is insignificant. The setup is very simple and is shown on the title picture. It consists of a toaster oven placed in a large plastic storage box, 5lb CO2 cylinder/regulator/needle valve, a length of silicone tubing and a box of matches. Since CO2 is heavier than air it won’t stay in the oven if pumped directly into it. Therefore, a container around the oven is needed. Since CO2 is not that much heavier than air it will raise when heated therefore a lid covering the container is helpful. A tube runs from a cylinder to the bottom of the box. Matches are used to check the inert atmosphere. I light a match and put it under the lid – if CO2 is there it will extinguish the match. Needle valve on the cylinder allows me to fine tune the flow, the heaviest gas loss will be during reflow peak when the temperature is the highest. I tested the system with some pretty stale boards with were lying around for a couple of years. The wetting was excellent even with standard soak time of 3 minutes. For soldering normal PCBs no changes in profile were necessary. The overall process doesn’t change too much either: I place a board in the oven and start it, then I open the cylinder and keep it open until the oven temperature has dropped to about 170C after reflow peak. I haven’t noticed any change in oven dynamics, however, opening oven lid after the peak increases cooling rate. If you already have a CO2 cylinder, this setup is inexpensive, quick to make and gives excellent results. I’m hoping to solder many boards with it – after about a hundred cycles the cylinder, which was about half empty when I started experimenting, still have plenty of CO2 in it. When I replace it with a fresh one I’ll start counting cycles to get a better idea of h