The Shepard Test Stand is a test stand for Estes rocket motors. It is named after Alan Shepard, America’s first astronaut, as it is our first test stand. We anticipate using an Arduino board to provide the physical interface between the data collecting computer and the required sensors. This project is the first in a series of projects to develop the required skills for the practice of safe rocket engine operation, and to develop the capability to measure and record data about a rocket engine’s performance. The use of Estes class motors provides a relatively safe environment to learn in before moving to higher powered motors and engines. The ultimate vision is to develop test stands for full scale liquid rocket engines for use in orbital launch systems.
Little clicky switches are standard input “buttons” on electronic projects. These work best in a PCB but can be used on a solderless breadboard as shown in this tutorial. The pins are normally open (disconnected) and when the button is pressed they are momentarily closed.
NEW PRODUCT – TIP120 Power Darlington Transistors – 3 pack. Transistors are powerful little electronic switches, and when our little NPN transistors aren’t power enough for your project, we have been known to use these beefy TIP120 Darlington transistors. Great for whenever you need to control medium to high-power electronics such as motors, solenoids, or 1W+ LEDs. We find them so handy, they come in a pack of 3!
Each transistor is a general purpose amplifier, model TIP120 and has a CBE pinout. They can switch up to 60V at peak currents of 8A (not continuously, just peak!) and continuous current of 5A, with a DC gain of about 1000. For more details, check the datasheet.
NEW PRODUCT – TO-220 Clip-On Heatsink. Get the most out of your regulators, transistors and other TO-220 packaged chips by clipping on a heat-sink. Your transistor or regulator may advertise it can handle high currents but when multiplied by the drop voltage, the Wattage may be too high for the bare chip! Most TO-220′s can disipate about 2W’s worth without a sink.
I was messing around with a personal project today (that’s what weekends are for, after all!), and was trying to get the current consumption on a small wireless board as low as possible in power-down mode (to keep the thing running for years of a single battery). I trust my Agilent 34410A, but measuring very low current can be a challenge, and I thought it was a good excuse to try out the uCurrent I picked up a while back from the shop here. $1400 DMM versus $60 red box, and the results were bang on. If you just need to accurately measure current, the uCurrent will definately leave a much smaller hole in your wallet without compromising on accuracy or reliabilty!
Something I really miss living in a big city (Paris) is that I almost never get to see the stars anymore. Some of my best memories in university were going out for walks at 3AM and just laying around in a field, looking up at the stars and being humbled by a sense of awe at the scale of ‘everything out there’. Chris Gammell posted a link to scaleoftheuniverse.com on twitter, and when I had a look it reminded me exactly what’s so amazing about the world we live in, and everything around, in, and above us. Great to be reminded to look up … and down … from time to time.
Please note, this is an ‘open collector’ driver – it can only be used to connect the load to ground and there will be a 1 Volt (or more) ‘drop’ across the internal transistors. The inputs can be driven by 3.3V or 5V logic. Fits nicely in any breadboard or perfboard.
Duane over at Screaming Circuits had a great little post today that reminded of a problem I recently had (again): the need for thermal relief on small surface-mount parts, particularly discretes. I’ve been working away on a basic <1GHz wireless board as a weekend project, and the first version of the board worked well, but the Balun between the RF transceiver and the antenna failed to properly reflow every time. It would shift to the bottom in the image above, and because it’s a fairly fine-pitch part (it’s the six-pin chip in an 0805 sized package), the other side was never properly soldered and wouldn’t work. A bit of magnification and some time with the soldering iron fixed it, but it was an avoidable problem and you can’t do rework in a production environment. (more…)
NEW PRODUCT – Solder:Time II DIY watch kit. Calculator watches are back, but microcontroller watches are always in style. Make your own with this easy to solder real time watch kit from SpikenzieLabs! It comes with a unique laser cut acrylic casing which protects the watch and looks snazzy besides: the four individual acrylic parts cut to fit the internal PCB, battery and switch perfectly. Included is a velcro wrist band. After soldering the Solder:Time II, the watch is built by stacking the acrylic parts with the PCB and holding it together with the included screws.
The Solder:Time II was designed to be a wrist watch. It doesn’t have to be limited to living on your wrist, you could also use it as a badge or desk clock.
This new version is even more hackable than ever. The on board microcontroller in this model is the very popular ATmega328P used in many of the current versions of Arduino™. In fact, you can reprogram your watch using the same Arduino™ IDE software that you use for a regular Arduino.
The Solder : Time II is different from the original Solder:Time in many ways. The display has been upgraded to a set of four 5×7 LED matrix modules. This gives you control of a 7×20 matrix for a total of 140 LEDs!
The new LED matrix allows for an amazing amount of information to be displayed; aside from the current time… The date, month, words, scrolling messages, graphics, special characters … the possibilities are endless.
The ST2 comes with a piezo buzzer for the alarm function, but you can also use it to add sounds to you custom programming and games.
Great looking laser cut acrylic case
Easy to solder
Stand alone project – no computer or other programmer required. Just solder it and it’s ready!
On board Dallas DS1337+ Real Time Clock (RTC) for super accurate time keeping
Jumper (on bottom) for always on use.
Hackable: Programming and I2C pads labeled on bottom
Clear front and back casing to show the internal electronics
Adjustable wrist band
Can be also be worn as a badge with optional badge clip.
Long lasting battery, with special LED lighting method and very low power processor sleeping.
Diameter: 63.5mm (2.5 in)
Thickness: 10.8mm (0.4in)
Weight: 43g (1.5oz)
This is a DIY soldering kit, you’ll need to assemble it yourself but luckily that is very easy, and very fast so this is a good kit for beginners! You’ll need basic soldering tools such as an iron, solder, and diagonal cutters.
Kit includes: Solder:Time PCB with all of the electronics, Laser cut acrylic casing with four screws, Easy to use Velcro type wrist band (long enough for huge wrists, trim-able for smaller ones and a CR2032 Battery. All instructions are here!
Eagle doesn’t always get a lot of love since it’s a proprietary SW package, etc., but having tried a variety of packages (both OS and pricey commercial ones), Eagle has a lot of little details that make it feel like a very mature package to me.
Eagle definately has it’s quirks, but once you get over them there’s an attention to detail that makes it far easier (personally speaking!) to be efficient than in some other packages I’ve tried, like being able to use the mouse scroll wheel on combo boxes to shift between layers or trace width, etc., without having to first click on the combo box. It’s a small detail, but the kind that makes a huge difference since you can focus on schematic capture and not clicking unecessarily on UI elements. Similarly, you can just start typing a command even if the command input box doesn’t have the focus. Love Eagle or hate it, that kind of attention to detail takes time to get right, and I appreciate a lot of little additions to the code like this.
I came across another little detail like that today that I hadn’t noticed before. With common parts that I use again and again in schematics (resistors, caps, GND/VCC symbols, etc.), I usually just place the part once via the ‘Add’ button, and then copy and paste it … but you can also right-click the ‘Add’ button to get a list of the last parts that you added to your schematics (any schematic, not just the current one). Have any interesting little tips yourself? Feel free to post them in the blog. I’ll have some more posts on this topic later this week as well!
If you have to work on a particularly dense board, you can’t really get away from using small vias: <=0.3mm/12mil drill bits and <=0.125mm/5mil annular rings. While unavoidable, using small vias and particularly small annular rings poses a problem during manufacturing, since there is inevitably some variability with the drill placement and the smaller the annular rings (the metal ring left around the drilled hole) the more likely you are to end up with a broken via. One easy solution to improve your yield of error-free boards is using something called ‘teardrops’. They fan the trace out before it joins the via, making a ‘teardrop’ shape, effectively increasing the size of the annular ring and reducing the risk of faulty vias.
Most packages include some means to create teardrops, and Eagle is no exception. The default installation includes a ULP called ‘teardrops.ulp’, which you can run by simply typing ‘ULP teardrop’ when your board file is open. One word of caution, though … you should only run the teardrop ULP on a seperate, renamed copy of your board file since the changes are irreversable!. Make a copy of your board names xxx_teardrops.brd, make sure the original schematic is closed, and then run “ULP teardrop”. Give it a try and you should get an idea of why they can be useful on tight-pitch boards like the image above, which was from a 6mil/6mil 4-layer board with 0.3mm drill holes and 0.1mm annulars.
Check your cable, connector and antenna to verify whether you need this adapter, or the other flavor. In specific, look for the center contact, is it an ‘innie’ or an ‘outie’? This adapter is likely best used for connecting an SMA antenna to a board with an RP-SMA connector.
The 288-cell Volt lithium-ion battery pack comprises four modules in a T shape that fits below the rear seat and in the “tunnel” between the front seats. Bus bars connect the four modules, and a service-disconnect bar connects to the pack contacts (Figure 1). The pack physically divides into plastic-encased slices, or blades, each of which includes two cells. A cooling fin carrying five channels of coolant separates the two cells. Electrically, groups of three cells connect in parallel, and 96 of these groups are in series so that the 288 cells produce 360V with a capacity of 16 kWhr. To prolong battery life, the battery never fully charges or discharges, so it uses only the “middle” 9.4 kWhr of battery energy.
NEW PRODUCT – Waterproof 2xAA battery holder. Keep your power source safe and toasty in these waterproof 2xAA battery holders. They’re just like classic switched battery holders, but designed for survival! The case has a rubber gasket around the edge of the case (its black and hard to see in the photos but it is there) and attaches together with 4 machine screws. What we like about this design is that the hexnuts are captive in one side and you can assemble/disassemble as many times as you need. There’s a potted power switch and a rubber-boot on-off switch (press to turn on/off). Use with any alkaline or rechargeable batteries for about 3V output.
NEW PRODUCT – 12 VDC 1000mA regulated switching power adapter – UL listed. This is a really nice power supply. It’s a switching DC supply so its small and light and efficient. It is thin so it fits in power strips without blocking other outlets. The output is regulated so you’ll get a steady 12V up to 1000mA (1 Amp) of current draw. 5.5mm/2.1mm barrel jack, positive tip. This supply is designed to work anywhere in the world, 100V-240V AC wall power, you’ll just need a low cost plug adapter.
New! This adapter is now CE / UL listed
Great for Boarduinos, clock kits and Arduinos, anything that has a 5V regulator! Also works great with 12V DC devices such as many solenoids, switches, our coin acceptors, analog-type RGB, cool white and warm white LED light strips.