[Dino’s] JFET Guitar Preamp With Piezo Pickup

September 12, 2011 by 10 Comments

This week, with a little help from a Roomba, [Dino] built a guitar pickup and preamp that sounds marvelous. A pickup takes vibrations from the guitar and turns them into an electrical signal which can then be amplified and broadcast. He grabbed a long-dead Roomba which has slowly but surely been donating its organs for his weekly projects. After plucking out a piezo element he grabbed a bag of Junction gate Field-Effect Transistors (JFET) and built a preamp circuit around one of them.

JFETs operate in much the same way as MOSFETs (which we took a look at last week). [Dino’s] design adds a few resistors and capacitors to tune the gain and decouple the circuit from the input and power rails. He epoxied the piezo element inside the guitar and connected leads between it and a jack mounted in the body. As always, he does an excellent job of explaining the concepts behind the design and outlining the build techniques that he used. We’ve embedded his video after the break.

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Inkjet Print Head Driver Shield

September 12, 2011 by 20 Comments

[Nicolas C Lewis] is churning out inkjet print head shield kits for Arduino. If you’ve always wanted to label or brand objects as part of a project this greatly simplifies the process. Using his all through-hole design, an Arduino can print at 96 dpi. At first we had trouble figuring out what we could use this concept for, but [Nicolas] has the answer. In is FAQ he links to a couple of his own flat-bed inkjet printer builds based on earlier prototypes, but he also links to other projects using the same concepts like the Nickel-O-Matic, or the ping-pong ball printer (we’ve embedded video of that one after the break).

The shield only requires five connections with a microcontroller. We love the jumper-based connection system that [Nicolas] chose which lets you use several print heads at once by selecting different drive pins. The project is still in the funding stage but is already over funded. Schematic and code will be posted as soon as the first production run is complete.

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PCB Drill From R/C Car Parts

September 12, 2011 by 17 Comments

[Sid] makes a few PCBs a month and the hardest part of his fabrication process is always drilling the through-holes. He has a PCB hand drill that usually results in a sore index finger. After a few unsuccessful attempts of using a full-size electric drill and not wanting to invest in a commercial solution, [Sid] made a PCB drill from a broken R/C car.

The toy car was donated by [Sid]’s 4-year-old after a terrible crash. [Sid] took the gearbox from the car and added a small circuit to control the direction of the drill. After attaching the drill chuck to the former R/C car axle and adding the power leads to a 5 Volt adapter, a PCB drill press was born.

Most of the parts for this build were salvaged from the toy car’s radio control circuit. Except for the chuck from [Sid]’s hand drill and a few switches, everything on this build was pulled from a broken remote control car. While the build is a lot simpler than this semi-automatic PCB drill, [Sid]’s drill seems to work well. Check out the demo video after the break.

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A Simple Fix To Resurrect Your Broken Iclicker

September 12, 2011 by 34 Comments

simple_iclicker_battery_fix

If you are currently attending college, the odds are that you are familiar with iclicker classroom remotes. If you have one of these, you might also be aware that they tend to be flaky at times, particularly when it comes to powering on. [Todd] received a few “broken” iclickers lately and has found an easy to fix design issue that might possibly save yours (and others) from the trash heap.

When he started pulling the units apart to diagnose them, he noticed that something with the battery contacts was not quite right. They are held in place by the device’s plastic shell which is pretty common, however in the iclicker, the portion of the plastic case that holds the positive battery contact is too big, preventing some batteries from making a complete circuit.

Now you might be thinking to yourself that AA batteries are all the same, but they are not necessarily created equal. Through a small bit of testing, [Todd] found that many different batteries experienced intermittent connectivity issues depending on the height of the positive terminal, and that due to their design, Duracell batteries flat out didn’t work. With the careful removal of a portion of the plastic surrounding the positive contact, [Todd] was able to fix each of his “broken” remotes.

He hopes that this information helps some people resurrect their non-functioning units, because a few minutes work sure beats buying another $30 iclicker.

geochron_world_clock_clone

World Clock Simulates Night And Day

September 12, 2011 by 10 Comments

[Justin] always wanted a GeoChron clock, but since they run in the range of several thousand dollars apiece, he was pretty certain he would never have the chance to own one. Undaunted, he figured out a way to build a small version of the clock for himself, and he wrote in to share how it was done.

He first purchased a Wise Clock 3 from FlorinC, but he definitely wasn’t going to use the clock as it was originally intended. Rather than display the time in numbers, he pulled the Wise Clock apart and sandwiched a vellum printout of a world map in between the front face plates. A tweaked firmware image allows him to simulate day and night using the Wise Clock’s LED array. He also programmed the clock to take into account seasonal light patterns, as you can see in the video embedded below.

We think this is a great idea, and though we would probably use plain white LEDs if we built one, the RGB LEDs in the Wise Clock certainly provide a neat effect.

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Announcing Our Next Theme: ATtiny Hacks

September 12, 2011 by 34 Comments

ATtiny Hacks Theme Banner

It is time once again to announce a new theme. This time around, we have chosen to highlight projects built around the ATtiny series of processors. These are 6 to 32 pin AVR processors that run up to 16 MHz and have anywhere from 512 Bytes of flash with 32 Bytes of RAM to 16K of Flash with 512 bytes of RAM. We’re guessing that this will be a pretty popular theme since so many people are using Atmel processors these days. If you have a project that you would like to see on Hackaday that is using an ATtiny processor, please hit us up on our tip line. If we like it, we may we choose to feature it in one of our daily themed hacks.

To kick off this theme, here is a nice write up about a stepper motor driver based around the ATtiny13. This project reads the analog value on pin B4 and adjusts the speed of the stepper motor. It is well documented and includes source code.

Glass PCBs

September 12, 2011 by 78 Comments

 

Our friend [Jeri] tipped us off about this cool video on youtube where the author makes his own “transparent” PCB’s using some nontraditional materials. One ounce copper foil is found online along with some clear glass microscope slides, from there it is just a matter of cementing the foil onto the glass slides with some thin UV curing glue. Once the 2 parts are mated the entire thing is popped into an eeprom eraser for its intense UV light, then excess is trimmed.

The normal routine of toner transfer is used to copy a circuit pattern onto the copper clad glass and it’s etched in standard ferric chloride. The copper is removed but the UV glue that was holding it is still left, some special care needs be followed as this stuff is pretty weak against even mild solvents, and you do not want your traces peeling up. Next no clean solder paste is applied and parts are soldered down with a heat gun, keeping the glass evenly heated to prevent it from cracking.
This leaves you with a board that looks like frosted glass, and in order to protect the glue while clearing up the frosted effect, some polyurethane is applied which fills in all the little bumps and smoothes the surface bout out to almost 100% clear.
The end application in this video is a touch sensitive board which works fine though the back side of the glass and presents a nice smooth interface for the user. Join us after the break for the video.

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