UptownMaker

With apologies to Quentin Tarantino... For a 10-year-old problem, the capacitor plague has been bizarrely present in my life recently. It started a couple of weeks ago when a coworker offered me an LCD TV that was "flaky" as scrap (my scraphound predilections are by now legend among those who know me). Being the upstanding gent I am, I pointed out that it was probably bad caps, and I found and replaced the buggers for him. A friend in Iowa sent me an e-mail, asking for help debugging a dead plasma he'd been gifted. He hasn't found bad caps yet but I'm fairly confident he will. My PC was dead the other morning, when I got to work. Guess why? A couple of months ago, I found a dead 17" LCD in the trash bin at the office. By now you should know how I fixed it. A tweep I follow posted this article this morning. This is fascinating for me in that it hits a number of points that people fail to understand about electronics: They wear out, but certain component...

A friend was asking after a circuit for making pulses from a pushbutton on push and release. Two ways immediately suggest themselves- using a PIC and using a differentiator. The PIC is easy for me, at least- I have a small stock of 12F683s which are 8-pin devices. Add a bypass cap and you're in business- you could even reprogram it to change the delay, debounce the input, etc. Of course, not everyone has a PIC programmer, and I feel like it's a pretty trivial app for a PIC, so I'll not talk much more about it. The differentiator circuit is a little more involved. Apologies for the crappiness of the image- LTSpice doesn't generate great output images, for one, and this was part of a larger image (it started NPN based, and generated negative going pulses; that's where Q3, Q4, etc etc went). V3 is the switch- in the application, it should be a 100-ohm pull-up to 5V and a switch that yanks C2 to ground when it's closed. R4 pulls up the base of Q3 and Q4, keeping the...

For those in the electronics world, SPICE simulation can be a great way to answer the "will my circuit work as advertised" question without breadboarding. It's a great sanity check- if it don't work in SPICE, it won't* work on a breadboard. LTSpice is Linear Technologies' own incarnation of SPICE. It's a nice little product, and comes with models for many of Linear's products (power supplies, op-amps, etc) along with many supporting components from other manufacturers (diodes, transistors, capacitors, inductors, etc) and generic parts (555s, LEDs, etc). Obviously, they provide it expecting people to download it, sim up a solution involving Linear parts and then sell eleventy-billion a year, thus providing a nice income stream for Linear (and it works- LTSpice makes it much more likely that I'll reach for a Linear part for power supply design than another manufacturer's parts). But for the tinkerer, it means that there's a free, very po...

A few weeks ago, I purchased 10 Atmega328P's from Mouser , naively thinking it would be easy enough to get them working on a breadboard as an Arduino sans the fancy (expensive) board. I was planning to use an FTDI USB to TTL serial data cable to bootload (I bought a 5V one, then realized that the two 3.3V ones I already had would work fine- lesson one of this saga). I also bought a some 16MHz crystals and the appropriate capacitors. At this point, I want to extend my thanks to whomever it was that decided a 6-pin AVRISP compatible ICSP header would be a value-add to the Arduino. I know that 95% of the Arduino users out there will NEVER use it, but I am very grateful. So, first hurdle- I figure I'll take one of the 328s and upgrade my Arduino (it was one of the, what, six? Duemilanove's that shipped with a 168 from the factory). Supposedly, the Arduino IDE has the capability of loading the bootloader onto a blank chip through an AVRISP, but I'll be buggered if I co...

Quick and dirty math post- The media reports the balloon was about 20' x 5'. Modeled in SketchUp as a 20' diameter sphere, shmooshed to a disc with a 5' vertical, that yields ~1000 cu. ft. of helium, or ~28,300L. As we all know, helium can lift 1.113g/L, for a total of about 31.5 kg of lift for that volume of gas. A quick Google search tells me the average 6-year-old boy weighs 46.2 pounds, or 21kg. That leaves 10.5 kg for the mass of the craft itself- about 23 pounds, or slightly less than the weight of three gallons of milk. I guess it's plausible, but I'm skeptical. I think it will come out that he was never on board in the first place.

Some general notes on the whole "Essential Skills" post. A couple of commenters mentioned that it is a bit heavy on electronics. True; partly that's because I'm an electrical engineer, but it's also because, in my experience, it's also where many makers (aside: I will continue to use that term; I came to my personal peace with it during the discussion about what to name the Twin Cities Maker group) "fall down" and lose confidence or run aground. Electronics is a massive sphere, and my hope, by including those things on the list, was to encourage people to develop familiarity with the most basic, most useful aspects of it (at least, as far as general making is concerned), rather than feeling overwhelmed by the whole thing and steering clear of electronics projects altogether. Some of the coolest projects I've seen were banged together by people with little or no electronics experience, just the confidence to go forward and the willingness to m...

@AntonOlsen recently posted an article on GeekDad enumerating 100 Essential Skills for Geeks. As he was inspired to do so by a list of "Essential Skills for Men", so I am inspired to make this list of essential skills for Makers. His list was a little long (100 items), terse (essentially one line per item, but with links), and slightly biased (heavier on computers than I might have liked, but to be fair, that is the most common geek fetish). I'm going to go for a shorter list, with slightly more verbose entries, and try to cast a wider net. If I get interest from this list, I'll follow up with an article on each point going into more detail. 1. Calculate power consumption and estimate battery life - Most electrical projects will involve batteries of some sort. Having an idea of how long your project will run on a battery can save you a lot of trouble later- that wireless garden soil moisture monitor is probably not going to run very long on a 9V battery. Mayb...

So, in keeping with our ethic of keeping our food as close to home as possible, Beth and I elected to put together a bit of a garden this year. Rather than do it on the ground, as is more usual, I built some boxes up on stilts. Being the ever-resourceful scrap hound that I am, I found some really good sources for the material to make these boxes: My work was clearing out a part of the factory and disposed of a demo dumpster FULL of various types of wood scrap. The bottoms of all the boxes came from some old shipping crates we no longer had a need for- they are rough-grade 1/2" plywood with a 2"x4" frame around the edge and one 2"x4" across the middle for extra support. 3'x4', pre-cut. Saved me a lot of effort and basically made the whole thing feasible. The legs are largely made from scrap I found on the side of the road. Someone had done some concrete work and left the wood on the roadside for anyone to pick up. Warning: wood used for a concrete ...

I know some of the people who read this blog (or who will see links to this post on Twitter) are into laser diode projects, so I thought I'd throw out some of the lore I've acquired on the topic. Laser diodes... 1. ...are current driven devices: Always drive them as such, being careful to limit the current through them to some relatively safe value. 30mA is not an unreasonable guess; as they age the current required for the same output power will increase. 2. ...aren't very laser-like: Don't expect a laser diode to put out a tidy little dot of light. That requires some optics. As the current pushed through a laser diode goes up, the efficiency of the device increases, and the divergence angle of the beam decreases. The beam tends to project an ellipsoidal shape on a perpendicular surface; the larger of the two dimensions will change more as the current goes up, while the smaller dimension won't change much at all. This is why laser pointers do not project a...

I got started late on the AMC, so I'm a few behind. I have, however, managed to average one a day since the 10th. I'm offline at home until May 6 (moved- why do I NEVER remember to arrange things like that ahead of time?), so I'll post my last one now. I have a ton of others, so I'll trickle them out, because I enjoy this, but this'll be it for the daily do. I'd like to include an RFID reader in a mouse. I think it's doable- some computer mice are pretty large, and by hacking ruthlessly at a hub and RFID reader, you should be able to do it easily enough. Why, you might ask? Quite simply, it would be a good way to keep your PC secure. Workplace hijinks can occasionally cause heartburn, so I know several coworkers who lock their PC when away from their desks. I'd prefer to have it lock itself after 2 minutes of no action, then have it automagically unlock when I get back to my desk. Thus, an RFID reader that detects a tag I have in a ring I wear an...

The MiniPOV is an Adafruit toy that provides a discreet package for POV (persistence of vision) display. Normally, POV displays involve lights that are mounted to a moving arm or wheel. As the lights are swept across a person's field of vision, the slow response time of our vision receptors causes us to detect the changing light patterns as an image. The MiniPOV depends on a person to provide the motion. Instead of being mounted to a moving object, the user holds it in his or her hand and sweeps it through an arc, providing the motion. That's pretty cool, but it's also kinda small- it fits into an Altoid tin. I'd like to make a larger one- say, 12" long, with one LED every half- or quarter-inch. My deeply subversive application is to press this up against the window of my bus as it drives past all the suckers stuck in traffic on the highway, flashing a message to hopefully get them to consider some alternative to single-commuter driving.

I used to have one of those super fancy Phillips electric toothbrushes. One of the cool features of it was that it charged by sitting in a cradle that inductively coupled to the toothbrush handle, so the handle could be sealed water tight and yet still accept a charge. I'm fascinated by this and by the potential associated therewith. I'd love to try using this for other applications. The easiest is a setup where a coil placed under a table passes power to a device sitting on the table, and the most obvious candidate would be a reading lamp or a centerpiece that has lights involved. The result is a cool centerpiece that lights up without the inconvenience of running a cord across the table.

This is a pretty common consumer product: a device approximately the size of a votive or maybe a tealight that behaves basically like a candle, in that it has a small LED that flickers and fades. The reason I want to make one rather than just buying it is that I have a special need- to be able to turn it on and off without contacting it. A few years ago I made some balsa and paper lanterns that can be hung from the ceiling on a string. A tealight in the bottom provides nice light, and the dozen or so that I made create a very warm atmosphere in a room where they are the sole illumination. Of course, lighting all those candles is no fun. It requires hauling a chair around the room, getting up and down, and trying not to catch the paper on fire. Putting them out is similarly taxing, unless you let them burn down over four to five hours. Obviously an application ripe for electronify-ing, but an electronic light has the same problem: to turn it on, you need to get up on a chair, pull...

Four, this time, because I know I'm going to go today and tomorrow without having another chance, since I'm moving tomorrow and I'm not going to have Internet access at home or work (eep). Tachometer glove for race driving- I USED to have a zippy car (VW Jetta GLI), and I always had a hard time knowing where the tach was. I thought it might be nice to have feedback that didn't rely on vision (because taking your eyes off the road at certain times can be...dumb is the best word I can find) or sound (because open windows, music, road noise, and other things can distract you from the actual sound of your engine. My idea was a pretty simple one- you put a pager motor on the back of a glove that fits snugly, so that the motor is held tightly against the bones to get maximum sensation. I'd guess a wireless link (Zigbee or Bluetooth or IR or whatever) would be most appropriate, and the motor would vibrate at a frequency either equal to or proportional to your engine RPM,...

My wife is pregnant. She is very interested in pursuing natural childbirth practices, and one of those is the idea that squatting during childbirth is preferable to being flat on the back. We have some concern that our chosen birthing "venue" (Fairview Riverside) may not have the necessary item for facilitating this position, and I desperately want to support my wife's birth plan, so I'm thinking about figuring out what exactly is required for this and trying to make it real and portable in the next six months. I'm guessing there are other women out there who might want this sort of thing as well.

I'm just going to give up trying to do one a day and go for two every two days. It seems more believable for me. I have a small interest in camping, which I'd like to make into a larger interest in camping. One of my very favorite camp toys is the penny stove -an ultralight alcohol fueled stove made from two Heineken cans and a penny. Yes, they do have to be Heineken cans- the shape is important. I have two of these little fellas and they work GREAT. A few mL of denatured alcohol into the stove is enough to boil a quart of water long enough to cook noodles, or make rice, or whatever. There are three other things I'd like to make in relation to these, though- a heat concentrator, a nice stand, and a larger burner version. In reverse order: Heineken comes in 12 ounce cans or 24(?) ounce cans. I'd like to buy a couple of the big ones and make an uberstove. Just for kicks. My current stands are two bent-up coat hangers. They require fairly level ground and are kind...

Two-fer today, to make up for yesterday. I wish I could get it together and post daily. The first is a simple Jacob's ladder. I've always wanted one of these and it's an affront to my tinkering nature that more than 10 years after I started into electronics, I still haven't made one up. The second is a raised garden bed for my vegetable garden. We'll be moving next week (eep!) and I have no interest in tilling up a large patch of yard in a rental property, and I'll need to buy some kind of soil to make it support plants anyway (there's little chance of success in the area I'll be living in without doing so, due to the advanced age of the neighborhood), so I'm thinking I'll build beds on legs, about two feet high and four feet by eight feet. I figure that'll make it easy to work them, and you should be able to reach the middle pretty easily. Good drainage, etc. My company has a demo dumpster FULL of old shipping crates made of 1/2" p...

I like the Arduino as a simple computing platform, but I've mentioned here before that I'd like to offload some of the more basic functions to a co-processor to let the Arduino have more CPU cycles for other stuff. That's true for many, MANY tasks, and one of the ones I've been fascinated with since college is the capturing and parsing of data from an infrared remote control. Adding IR to your project is a SUPERB way to add very complex I/O. I'm not sure if the Arduino has a library to read IR from remote controls, nor do I care, because it's likely to suck up an unacceptable number of CPU cycles. Thus, the IRduino: a shield with a small microprocessor (I'll probably use a PIC, since I know how to work those much better than AVRs) which decodes the signals from infrared remotes, packs it into three or four bytes (there are actually a LOT of possible codes out there, due to the number of encoding schemes). There would then be several options for sending t...

So, since DHS can swipe your stuff at a security checkpoint for no good reason, I've been thinking I might like to make a self-destructing USB drive. There are two possible tacks for this: one, a "snappable" drive where there's a small ampule that one would crush (a la cold war suicide pills) that connects an on-board 3V lithium battery backwards across a couple of pins, roasting some silicon and making the drive pretty much irrecoverable. I guess in the end, it would be difficult to completely wipe out the entire flash matrix, but it's a start. This has a disadvantage in that you need to KNOW someone is ABOUT to take your flash drive away in order to activate it. The other method is a simple wire and switch method, where the drive is modified to reverse the 5V and ground unless the user does something to reverse that. The easy way is to put a switch on the drive which has to be flipped; that of course draws attention to the mechanism. A subtler method involve...

In canning, when making sauce or jelly, the easiest way to go is to use a strainer to separate seeds and peels from the desired fruit meat. The drawback is you get crank arm eventually, because you have to turn the crank for sometimes up to a couple of hours at a stretch and, while it's not terribly physically demanding, the long throw of the crank means that your whole arm is involved which can really wear on the joints. To that end, I've decided to make myself an adapter that will let me join my strainer to the PTO (or whatever it's actually called) on the front of my KitchenAid mixer. I bought a couple of universal joints at Ax-man that should do the trick nicely (necessary because the height of the mixer PTO and the height of the mill axis are not the same; I considered making a platform that the mixer can sit on and the mill could clamp to which would position the two machines to be coaxial but frankly, I'm not crazy about having to line them up THAT carefully ...

Canning in the house sucks. It involves putting a pot of water on to boil for hours at a time (some canned goods must be boiled for 30 minutes or more, and if you're doing it, you probably want to do enough to make it worth your time, so that means several rounds), tying up the whole kitchen, and release about a bazillion joules of heat-energy into your home. By the way, did I mention that this can only be done during the hottest months of the year? Yeah. Beth and I are moving into a rental house in a couple of weeks, and I'd like to make an outdoor canning kitchen (I bet you though ALL my projects were electronics...). What I have in mind is a couple of those turkey deep fryer things, connected together through some kind of Y-valve, with a nice frame of some sort to add stability. A bench, too, probably. I can't build this stuff in because this is a rental, so it'll be an interesting challenge to see how I can do it.

(click to enlarge) I'm not going to count this in the April Maker challenge. I don't know why. I hacked together a really hokey power supply for my tabletop foam cutter and as-yet-unbuilt acrylic bender (although strictly speaking, the portion of the foam cutter heating element that runs underneath the acrylic "table" has done a nice job of melting it). JTBarclay is using it for driving a 24V nigh-5W fan under a stir-plate, and Pat is building one for HIS foam cutter. It does a fairly good job, although it has no check on the amount of current it draws from the unregulated DC supply, which is a MAJOR short coming. The IC is an 8-pin PIC that I've programmed with a PWM controller that reads a pot to determine the duty cycle (at least, in this configuration it does). Because of the way the design works, you can put a limit on the duty cycle by inserting a resistor between the potentiometer and the ground rail. Using a smaller potentiometer is wise if you were ...

I keep falling behind, but I'll not be more than one day back, dammit! Number 6- A mini-lathe. One of the most common things I use a lathe for is the drilling of a concentric hole (or reaming one out) in a circular object (gears and wheels, for instance). I don't need a super-accurate means to reduce a diameter or things like that, just a way to put a hole in the exact center of a gear when I'm trying to mate it to a particular shaft (of a potentiometer, or encoder, or what have you). I guess "lathe" is the wrong term, but it's the best I have. Number 7- RepscRap. The RepRap, of course, is the open-source self-replicating 3d part printer. The RepscRap is an extension to that, a device which allows the reclamation of plastic material of appropriate composition by shredding it, melting it, and extruding it as a stick or rod the can be re-used in a RepRap. The material would be recaptured from junked electronics, pop bottles, or whatever uniform source of a...

I'm a day behind so it's a two-for-one, but a quickie, because I'm behind in every possible metric my life could be measured in. Number 4 is a tabletop hot-wire foam cutter. Imagine a scrollsaw or bandsaw, but instead of a saw blade, using a piece of hot wire. It excels in cutting intricate shapes out of pieces of expanded polystyrene foam, and can be used on other thin and low-density plastics as well. Number 5 is an extension of this. By putting the hot wire at the edge of a table, along the corner, a piece of acrylic can be heated evenly along a line, which will allow it to be bent. Both of these use the same power supply. That will be described as a future project.

Tamiya is a Japanese company that makes many hobby-type products- model kits, "experiment" sets, RC toys, and others. Deeply buried in their product line is a set of generic motor/gearbox combinations. These range from very simple to very complex; I have a couple of their high-power ones, and one of the 6-speed ones as well. They are well constructed, fairly tightly toleranced, and loaded with features. The have a twin-axis gearbox, a worm drive gearbox, and a planetary gearbox, in addition to more "standard" types. Typical cost is between $10 and $20, depending on the model. One of the most enjoyable items in the hobbyist robotics arsenal is the RC servo. However, most servo motors tend to be either pricey or weak, and they tend to be non-reconfigurable, meaning that you can't readily trade off speed for torque or vice-versa. To that end, I'd like to make a small PCB that would let me take an input from a shaftless potentiometer attached to the output ...

Lately I've become obsessed with multiprocessing solutions for hobby level embedded systems. A PIC12F683 is a reasonably powerful 8-bit microcontroller in an 8-pin package, and it sells for right around $1 in qty 25. This can provide a powerful means for offloading certain functions of a circuit to another IC at minimal cost, allowing you to do heavier lifting in your main circuit than you otherwise might have. An example is servo-motor control with the Arduino. It's quite do-able, but you may find yourself in a project where you want to control a servo's rotational position based on user input from a potentiometer. In that case, using precious CPU cycles from the Arduino in the system just to read the pot and update the servo periodically is a drag. So why not take an 8-pin PIC and make a simple IC that reads digital inputs and converts the value to a servo angle? It'd be easy enough- the servo output is a PWM signal but the duty cycle is low. The motor holds po...

Over on the TCMaker web forum , a challenge was levied to all of us to come up with one project every day during the month of April. I'm behind, because I've been VERY busy preparing for and teaching my intro to electronics class through Studio Bricolage , but I'm going to try VERY hard to keep up with it for the rest of the month. Hence, the new blog. Project 1: Airsoft pellet gun organ Ax-man sells Airsoft pellet guns super cheap (~$10 for a pistol). I'm thinking it might be fun to try to make a pipe organ that articulates based on having the pellets fired down the pipes, which would then dump the pellets into a bin for immediate re-use. It might get pricey, since I'm thinking I'd want the seven major notes, but I'm not sure how I'd go about tuning them or even what effect firing a pellet down a tube would have. Still, it might be cool to try out.