Fabricating custom displays for a commercial coffee roaster


Roasting the perfect coffee bean is an art form. But even the most talented of roasters can use a little feedback on what’s going on with their equipment. [Ludzinc] recently helped out a friend of his by building this set of 7-segment displays to show what’s happening with this coffee roaster.

The yellow modules hiding underneath the display panel are responsible for setting the speed of the hot air blower and the rate at which the drum turns. They’re adjustable using some trimpots, but it sounds like the stock machine doesn’t give any type of speed feedback other than direct observation.

The solution was to patch into those speed controllers using the ADC of a PIC chip. They each output 0-10V, which [Ludzinc] measures via a voltage divider. After the speed is quantified the microcontroller outputs to one of the displays. Since there’s a different chip for each readout, the firmware can be custom tuned to suit the operator’s needs.

Keep this in mind if you’re still planning to build that coffee roaster out of a washing machine.

Laser Kaleidoscope uses more 3D printing and less scavenging


At first we thought that [Pete Prodoehl] was using the wrong term when calling his project a Laser Kaleidoscope. We usually think of a kaleidoscope as a long tube with three mirrors and some beads or glass shards in one end. But we looked it up and there’s a second definition that means a constantly changing pattern. This fits the bill. Just like the laser Spirograph from last week, it makes fancy patterns using spinning mirrors. But [Pete] went with several 3D printed parts rather than repurposing PC fans.

In the foreground you can see the potentiometers which adjust the motor speeds. The knobs for these were all 3D printed. He also printed the mounting brackets for the three motors and the laser diode. A third set of printed parts makes mounting the round mirrors on the motor shaft quite easy. All of this came together with very tight tolerances as shown by the advanced shapes he manages to produce in the video after the break. Continue reading “Laser Kaleidoscope uses more 3D printing and less scavenging”

Add motorized blinds to your home theater


[Chipsy] found himself with an interesting problem. The room that serves his home theater has a wall mirror which reflects part of the screen during viewing. In an otherwise dark room this was very distracting. His solution was to add a blind that covers the mirror during viewing, but who wants to constantly pull that down and back up again? Since the motorized projection screen he is using has a remote control he figured out a way to motorize the blind and synchronize it with the screen’s remote.

The screen uses mechanical relays to switch the motor. He patched into these with an Arduino to detect whether the screen was going up or down. It was easy enough to use his own relay and motor with the blind, but he needed a way to stop the blind once it was in position. For covering up the mirror he simply sets an 18 second timer, but for retracting the blind he wanted precise alignment so he added a magnet and sense its position with a reed switch. See the synchronized screen and blind in the clip after the break.

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Repair your ice maker motor without buying a whole new assembly


There are a number of things that can go wrong with an automatic ice maker. But one of the more common problems is that the motor which scoops the ice out of the integrated trays can burn out after years of use. [Dave] recently repaired a common ice maker motor and shows us how cheap and easy it can be. See how he did it in the video after the break.

Pictured above is the motor and gear box from the ice maker. Before disassembly he verified that the problem is with the motor by placing a piece of paper in the path of the fingers that move the newly formed ice. After removing the sensor arm and three screws he was able to pull this front portion from the unit. The two wires are clipped as near to the motor as possible and the motor itself comes out with just a twist. After verifying that the gears are not broken he sourced a $2.50 motor replacement by Googling the part number (M004 3W in this case). Once the new unit arrived the motor wires are connect in much the same way that a punch down Ethernet jack makes a connecting with insulated wires.

This is something worth looking into if your ice maker is not working. The manufacturer may suggest replacing the entire unit which can be well north of a hundred bucks… this is a worthwhile gambit to save some cash. Well, we guess you could always build your own non-electrical ice maker.

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Scratch-built motor uses a clever design

[Lou] is on a hot streak when it comes to interesting builds. This time around he made his own motor using wood, PVC, some fasteners, and a bunch of enameled wire.

His method of building a commutator is intriguing. He first builds a rotor by cutting two opposing sides off of a PVC four-way connector and pushing a short galvanized pipe through what’s left. After adding two PVC nubs with caps and nails as pivot points he wraps the PVC and metal pipe with a continuous length of enameled wire. The enamel is then sanded off the windings around the PVC, and half is covered with electrical tape. The spinning rotor will cause the brushes to contact the bare wire during half of the rotation, and be insulated by the tape during the other half. The video after the break shows the motor in action, then walks you through each step of the build.

If you liked this video you should check out [Lou’s] water bottle rocket launcher, or his automated Ping Pong table topper which stores the game in the ceiling.

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Building an electric-powered longboard for under $100

[Alan] doesn’t have to kick to get around town because he added a removable electric motor to his longboard. It looks great, and works just as well because he didn’t reinvent the wheel. The idea is a mashup of an electric Razor scooter and his long board.

The majority of the project revolved around mounting everything he needed to the board. When it comes to the drive wheel he designed a tension system. When a rider is not on the board the back wheels of the long board are off the ground by about an inch. The springs in the suspension system make it so when you do mount the board all wheels are touching, with the main drive wheel held tight to the pavement even while turning.

Unlike some electric skateboard builds [Alan] didn’t need to raise the board off the ground as the battery compartment is mounted on top of the deck. He added cooling fans for the hot summer days, and even used velcro to attach the charger so that he can juice it up when away from home. Check out his three minute show and tell embedded after the break.

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Robot servo control using smartphone audio jack

[Jim] has an old Android phone he’d like to use as a Robot brain. It’s got a lot of the things you’d want in a robot platform; WiFi, Bluetooth, a camera, an accelerometer, etc. But he needed some way to make the mobile, mobile. What he came up with is a chassis with servos that can be controlled by the phone’s audio port.

To start his adventure he crafted a square wave audio file in Audacity and then played it back on the Android music player. By monitoring the output on an oscilloscope he found the wave was well produced, with peaks of about 1V. With that in mind he designed a circuit using two transistors to amplify the signal, thereby creating a usable input for the servo motors. Each motor has one of these circuits connected to it, with the left and right channels from the audio jack driving them separately. In the clip after the break you can see he even wrote a simple Android app to extend the idea to a more usable level.

This is a similar technique as used by the recon robot we saw about a year ago.

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