- How do I add an event to the Calendar, WordPress, Facebook, Twitter?
- Starting up and shitting down the space.
- Where is the light switch?
- Windows, doors, ect.
- How to Add/Remove someone from the members mailing list?
- How to expense claim space
- Request for consumables
- Garbage and recycling
- How to do E-Waste bins.
- What is the contact info for the landloard.
- Where the procedures live and how to edit the wiki
- Google docs, DropBox, Wiki, ect..
- What goes on each mailing list, general or members
- How to use the overhead projectors
Cut on VHS’s Laser cutter, The Moose Head Jewelry Stand up-sized to live size.
Made by fishboy.
Pictures from the Lithium Charger Build Night,
I will provide the schematic, build guidelines and setup instructions, plus any parts that are not already at VHS. You will need to bring a DC power adapter of 7.5-9V and at least 800mA rating. If you can only find an adapter rated at 500mA, you will build your charger to suit, otherwise you will build a 700mA charger. Sorry but there seems to be a distinct lack of adapters in this voltage range at VHS, so go and rummage through your junk pile. Also bring a trusted multimeter if you have one, and an enclosure if you want one. And if at all possible, bring a power jack to match the connector on your AC adapter, especially if it’s an odd size, or you may have to hard-wire it to your charger board.
The build will involve 16 components, soldered to perf-board or vero-board (I haven’t decided yet), so skill rating is intermediate. If you haven’t done any electronics it is probably not the greatest entry point. Depending on how this turns out, we could get boards made up for a second build night. PCBs would simplify the build, but it would be helpful to have some early adopters to get the wrinkles out first, hence the idea for this first build to leave some room for individuals to bring their own ideas to the mix.
This is just a quick note with some extra info for those who attended the lithium charger build.
- The barrel jacks with the short wires attached that some of you used to connect your board to your AC adapter should be replaced. Their wires are really too thin for the current we ask them to carry and also too thin to make a durable connection with the board. Best to solder your power supply directly to the board, I think.
- Further experiments show that it’s difficult to charge the Nokia phone batteries at currents over about 500-600mA without the voltage hitting its upper limit. For anyone who built a high-current charger and who’s found that it won’t latch in charging mode, that’s likely the reason. Other formats of lithium cell (like the cylindrical 18650 type found inside many laptop and RC battery packs) should be able to take higher charging currents, though.
- I’ve found that the connection to the battery is a critical point of detail. Since charging will stop if the connection is interrupted for a fraction of a second, you really need these contacts to be flat blades of a good thickness. Otherwise, if the light goes out (meaning the battery is charged) it may just be that a fruit fly landed on the battery and moved it by a few microns. There is brass sheet at the Space which is easy to cut and solder, so I recommend making that upgrade.
Finally, I can’t resist sharing an image of my just-built rechargeable TV-B-Gone getting a fill-up. The phone battery is perfect for this application and it’s simple to connect a charging cable to the ISP header (just make sure you get it the right way round!).
- What is geocaching?
- What do I need and how is the game played?
- Where do I find a list of geocaches?
- What are the rules of geocaching?
- What are Trackables?
As voted at the last AGM, The VHS is now holding quarterly GMs. The next GM is 13:00 October 28 at the VHS. All SMART voting proposals must be submitted to the agenda by the 14th so that members can have time to discuss them on the members-only mailing list. The quarterly GM will feature updates from the committees, our latest financials, voting on the proposals and then possibly pizza. This is a members-only event.
Are you worried your wiring fixes might not be the safest? Come to the VHS and learn about soldering, flux, helping hands, heat shrink, and how to tell good soldering from bad. If there’s enough interest we’ll run a second class right after the first. Remember: keep your tip clean!
Please RSVP to aggrav8d chez hotmail.com.
$5 for non members, free for members.
Starts at 13:00 on Sunday, October 21st @ the VHS.
PS: You’ll also notice a new cateogory for posts – Courses! Of course we got courses, we’re coarsly coarse about courses at the VHS. Only makes sense to make them easy to find. Check ‘em out, take a course, lead one yourself! Are they the aerobics section of the brain gym? You tell me in the comments below.
Back by popular demand!
Who: YOU! If you can climb two flights of stairs, you’re welcome. For the rest of you, we’ll find a way to accomodate.
What: We bring everything. You bring a cup! Learn about Arduino, circuits, and programming through hands-on learning at your own speed. Maximum 20 people, so please RSVP to aggrav8d chez hotmail.com. Price is $10 members, $20 non-members.
When: 13:00-16:00, Sunday, October 14th 2012.
Do you have an urge to see a class at the VHS? Comment below and we’ll try to make it happen.
Robert, a skillsaw, and I added a new shelf, designated EL-E. That’s (theoretically) room for ~20 more shoe boxes full o stuff. Special thanks to Tim and everyone who came out to the “How to Patent II” night for their patience with our noisy equipment. Notice how much room there is on the electronics bench? Let’s try to keep it that way. If you find something that doesn’t have a home, put it in the 2 week bin. If you think it should have a home, label it with an address.
Did you know? VHS has an address system for most stocked materials in the space. Ask someone about it next time you visit and then you’ll know how to find the things you need.
How do they deal with dishes in other hackspaces? I’m the dish guy @ VHS and, frankly, I’m tempted to donate them to the sally anne and supply paper cups at $0.25/ea donation. It would eliminate the dirty cups hygiene challenge, free up space in the kitchen, encourage the “pack it in, pack it out” rule, and generate revenue for the space – all while being environmentally friendly. Discuss in the comments below!
Amazing VHS Member & Bag of Mostly Water Simon wrote a great expose on lithium ion batteries to the members list. It was so insanely amazingsauce that we just had to share it with you. You can also find this permanently on our wiki here. Enjoy!
Thanks to the support of His Excellency, the Great Steve of Stevemopolis, we now have an abundant supply of lithium-ion rechargeables.
Since many people might be using with lithium batteries for the first time, I thought I would mention a few guidelines for those unfamiliar with this most excellent of energy storage media. Lithium cells are not difficult to charge correctly, but they are very particular. To paraphrase a well-known american street sign, “Differ and it will hurt”. The hurting could potentially involve fire and lithium-flavoured brimstone.
Charging consists of a constant-current phase, during which the voltage rises, followed by a constant voltage phase where the voltage is not allowed to exceed a certain value, while the charging current steadily declines. Commercial chargers typically set Vmax at 4.2V. By setting the voltage limit a bit lower (4.1V, say), you can be kinder to the cell and get more useful charge cycles out of it by preserving its capacity for longer. That is one advantage of setting up your own charge control circuit. The constant charging current, in milliamps, should not exceed the cell’s capacity, expressed in milliamphours. Charging current (in mA) is most often in the range from 0.5C to 08.C, where C is the capacity in mAh. You will find lots of ideas for chargers online, so make sure that they conform to this pattern. One of the simplest to build consists of an LM317 configured for current limiting feeding into another LM317 configured for voltage regulation.
You can even charge a Li-ion cell from a current-limited bench power supply. Set the voltage to 4.1V and the current limit to 500mA (which is a safe value for a 1200mAh cell). You will see the transition from the first to the second phase of charging as described above. The charging that occurs after the voltage limit is hit is known as the saturation charge. It accounts for the last 20% or so of the energy stored in the cell. Reducing the length of time spent in this second phase reduces the energy stored, though not by much, and is less stressful to the cell. Typically charging is terminated when the charge current has dropped to a certain percentage of its initial, current-limited value. Try 50% as a starting value.
If you don’t want to build your own charger, you can get ICs to do the work for you. The MAX1555 (free samples available from Maxim) and the cheaper MCP73831 from Microchip are two examples. The only trouble with them is the tiny surface-mount SOT-23 package, so you really need to make up PCBs if you go that route Alternatively, for a bit more $$$, Sparkfun has various breakout boards based on these chips. Just put “LiPo charger” in their search box. If you want to get fancy, you can integrate the charge control with your main MCU. That introduces a lot more complexity and work but obviously has the potential to shrink your BoM. Whatever you do, don’t just leave a lithium cell hooked up to 5V through a resistor. That can sometimes be OK with NiMHs but never with lithium, as the voltage will continue rising past the safe maximum of 4.2V!
If you want to ensure that your application receives a constant voltage regardless of whether or not external power is connected, consider using a low-dropout regulator like the MCP1700. That way, your application sees a constant 3.3V – enough for most MC’s and LED’s.
Equally important as overcharge protection is overdischarge protection. Don’t allow a lithium cell to discharge below 3.0V. If you go much below that, the battery can suffer internal damage which can reduce its capacity and potentially render it unsafe (i.e. a future fire risk). In practice I would recommend switching the device off either manually (in response to a low-battery warning light, for example) or, better, automatically, at 3.5V. The automatic option requires a bit more thought but can be implemented using an analog input and a digital output on a microcontroller, so it’s a good option if you are already using an MC. In one scheme, the pushbutton momentarily applies power to the MC, which immediately secures its own power supply through a transistor in parallel with the switch, so when the button is released, power continues to flow. Using a momentary-ON pushbutton for power ON/OFF rather than a traditional toggle switch is a nice ‘professional grade’ touch for any project.
What if your project needs more than 3.7V, or demands high current capacity? Certainly, multiple cells can be wired in series for increased voltage or in parallel for increased current and or run time, or a combination of the two. HOWEVER, charging multiple cells in series or parallel is best considered a field for advanced Ninjas. Unless (and, possibly, even if) the cells are identical and are wired into series/parallel configuration when brand new, there is scope for the charging voltage to be unevenly divided between cells wired in series, and for the charging current to be unevenly divided between cells (or strings of cells) in parallel. There are no safe & simple shortcuts that I know of to deal with these scenarios. Therefore, if you want to use lithium cells in series and/or parallel, you should disconnect them and charge them INDIVIDUALLY.
Why are there three terminals? Two are obvious (hopefully!) The third is a temperature sensor which can be monitored to identify fault conditions. It is not necessary to connect anything to this terminal when charging or using the cell.
You can find much more detailed information, values, charging profiles, graphs etc at www.batteryuniversity.com.
Be careful and be safe when charging lithium batteries. The information in this email is correct to the best of my knowledge but is not meant to be exhaustive or to cover every possible scenario. If in doubt ask for help or use a commercial lithium battery charger. Note: Most phone ‘chargers’ do not in fact contain any charge control electronics, because this function is integrated into the phone. So hacking an old phone charger to connect it directly to a phone battery is NOT a safe charging option.
As Super-Awesome Sylvia would say, “Remember to experiment, stay safe, and get out there and make something!”
I’ve been working on a project involving an Arduino Mega 2560 and a bunch of LEDs and electroluminescent wires. The application was to control a wearable lightsuit which responds to outgoing MIDI messages from a sequencer (Ableton Live in this case). It’s now officially up and running and has been out in public, with very positive results. Particular thanks go to Aaron Thul for his enthusiastic assistance throughout but really to all of you as a whole and to the Hackspace for providing such a supportive environment, and such a well-provisioned workspace. I already have plans for a new suit so you may be seeing me again soon ;)
Without further ado, I present the technosuit:
- Arduino Mega 2560
- El Escudo Dos (an electroluminescent wire shield)
- MIDI Shield (both from Sparkfun)
- Macbook Pro running Ableton Live
- Access Virus Snow synth
- M-Audio Axiom 49 and Trigger finger MIDI controllers
MIDI channels within Ableton Live are programmed alongside the music to play specific patterns on different zones on the suit, using arpeggiator plugins to create quick and complicated sequences. A USB MIDI interface sends that midi information out to the MIDI shield. Processing code on the Arduino interprets incoming “note on” and “note off” messages, and each light or el-wire responds to one discrete note
More information can be found here http://www.darkarps.com/