Pump Up the Volume with the 3D Printed Syringe Pump Rack

Syringe pumps are valuable tools when specific amounts of fluid must be dispensed at certain rates and volumes. They are used in many ways, for administering IV medications to liquid chromatography (LC/HPLC). Unfortunately, a commercial pump can cost a pretty penny. Not particularly thrilled with the hefty price tag, [Aldric Negrier] rolled up his sleeves and made a 3D-printed version for 300 USD.

[Aldric] has been featured on Hackaday before, so we knew his latest project would not disappoint. His 3D Printed Syringe Pump Rack contains five individual pumps that can operate independently of each other. Five pieces are 3D-printed to form the housing for each pump. In addition, each pump is composed of a Teflon-coated lead screw, an Arduino Nano V3, a Pololu Micro stepper motor driver, and a NEMA-17 stepper motor. The 3D Printed Syringe Pump Rack runs on a 12V power supply using a maximum of 2 amps per motor.

While the standard Arduino IDE contains the Stepper library, [Aldric] wanted a library that allowed for more precise control and went with the Accelstepper library. The 3D Printed Syringe Pump Rack has a measured accuracy of 0.5µl in a 10ml syringe, which is nothing to laugh at.

Syringe pump racks like [Aldric’s] are another great example of using open source resources and the spirit of DIY to make typically expensive technologies more affordable to the smaller lab bench. If you are interested in other open source syringe pump designs, you can check out this entry for the 2014 Hackaday Prize.

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Fixing A Product Design Flaw In A Misting System

[Xerxes3rd] works at a place where they raise reptiles in terrariums. Such enclosures require controlled lighting, temperature and humidity. Humidity is maintained using “misting” devices. These are usually water containers with a pump whose outlet ends in a series of very fine spray nozzles which create the mist. A timer controls the pump’s on and off cycles.

[Xerxes3rd] purchased an Exo Terra Monsoon RS400 misting system – a low-cost misting device and soon discovered that it had a serious design flaw. The built-in timer malfunctions, and it mists a hundred times more than it should! A lot of folks who buy a product and discover it has an inherent design flaw will return it back for a refund. Instead,  [Xerxes3rd] decided to break in and fix it instead –  “warranty void if tampered” be damned.

To start with, he needed to figure out what the problem was. He went about it in clinical fashion, eventually creating a slick document (PDF) outlining his observations and diagnosis. The timer controller board has a PIC micro, some buttons, potentiometers, LED’s and an IR receiver. The misting cycles are set using the two potentiometers – Off time and On time for the pump. His analysis and resolution makes for interesting reading.

What he found was that the PIC micro was reading inconsistent values from the potentiometers. More specifically, the software isn’t doing any smoothing on the analog values it reads from the potentiometers. Since the PIC that controls the system wasn’t easily re-programmable, he opted to replace it with an Arduino Nano. At the same time, he got rid of the potentiometers that were used to set the misting frequency and duration, and added a 16×2 LCD. Time setting is now done using the three on board buttons. He removed the PIC micro and replaced it with two female header sockets, onto which he plugged a small board containing an Arduino Nano and a few components. He also cut the original PCB in half, removing the potentiometers and crystal oscillator in order to make room for the 16×2 character LCD.

The lizards are now probably thanking him for their perfectly timed doses of moisture. Having done this, he could probably add in more features such as a temperature-humidity sensor, a water level sensor or maybe even throw in an ESP8266 module and have the Lizards tweet when they need to be hydrated. Because that’s another thing hackers love – feature creep.

Take a Spin on this Voice-Controlled 3D Scanning Rig

[Aldric Negrier] wanted to make 3D-scanning a person streamlined and simple. To that end, he created this voice-controlled 3D-scanning rig.

[Aldric] used a variety of hacking skills to make this project, and his thorough Instructable illustrates this nicely. Everything from CNC milling to Arduino programming to 3D-printing was incorporated into the making of this rig. Plywood was used to construct the base and the large toothed gear. A 12″ Lazy Susan bearing was attached to this gear to allow smooth rotation. In order to automate the rig, a 12V DC geared motor was attached to a smaller 3D-printed gear and positioned on the base. When the motor is on, the smaller gear’s teeth take the larger gear for a spin. He used a custom dual H-bridge motor driver made by a friend, which is connected to an Arduino Nano. The Nano is also connected to a Bluetooth module and an ultrasonic range finder. When an object within 1-35cm is detected on the rig for 3 seconds, the motor starts to spin, stopping when the object is no longer detected. A typical scan takes about 60 seconds.

This alone would have been a great project, but [Aldric] did not stop there. He wanted to be able to step on the rig and issue commands while being scanned. It makes sense if you want to scan yourself – get on the rig, assume the desired position, and then initiate the scan. He used the Windows speech recognition SDK to develop an application that issues commands via Bluetooth to Skanect, a 3D-scanning software. The commands are as simple as saying “Start Skanect.” You can also tell the motor to switch on or off and change its speed or direction without breaking form. [Aldric] used an Asus Xtion for a 3D-scanner, but a Kinect will also work. Afterwards, he smoothed his scans using MeshMixer, a program featured in previous hacks.

Check out the videos of the rig after the break. Voice commands are difficult to hear due to the background music in one of the videos, but if you listen carefully, you can hear them. You can also see more of [Aldric’s] projects here or on this YouTube channel.

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Arduino Synth Guitar Really Rocks

[Gr4yhound] has been rocking out on his recently completed synth guitar. The guitar was built mostly from scratch using an Arduino, some harvested drum pads, and some ribbon potentiometers. The video below shows that not only does it sound good, but [Gr4yhound] obviously knows how to play it.

The physical portion of the build consists of two main components. The body of the guitar is made from a chunk of pine that was routed out by [Gr4yhound’s] own home-made CNC. Three circles were routed out to make room for the harvested Yamaha drum pads, some wiring, and a joystick shield. The other main component is the guitar neck. This was actually a Squire Affinity Strat neck with the frets removed.

For the electronics, [Gr4yhound] has released a series of schematics on Imgur. Three SoftPot membrane potentiometers were added to the neck to simulate strings. This setup allows [Gr4yhound] to adjust the finger position after the note has already been started. This results in a sliding sound that you can’t easily emulate on a keyboard. The three drum pads act as touch sensors for each of the three strings. [Gr4yhound] is able to play each string simultaneously, forming harmonies.

The joystick shield allows [Gr4yhound] to add additional effects to the overall sound. In one of his demo videos you can see him using the joystick to add an effect. An Arduino Micro acts as the primary controller and transmits the musical notes as MIDI commands. [Gr4yhound] is using a commercial MIDI to USB converter in order to play the music on a computer. The converter also allows him to power the Arduino via USB, eliminating the need for batteries.

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Hypno-Jellyfish is Great for Kids (and Kids at Heart)

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LED’s are fun. They are easily seen, not to hard to hook up, and produce a nice glow that can be gazed at for hours. Kids love them, so when [Jens] daughter was born, he knew that he wanted to create a device that would alternate colors depending on the object’s movement.

He utilized a mpu6050 accelerometer to detect changes in position, and wired together an Arduino Nano, a 9V battery, and a 12 LED neopixel ring from adafruit. Design requirements were jotted down beforehand ensuring that any child playing with the Hypno-Jellyfish would not be injured in any way. For example, anything that fits in a child’s mouth, will go in that child’s mouth; meaning that any materials used must be non-toxic, big enough not to be swallowed, and drool proof/water proof. The kids will pull, and throw, and drop the toy as well, so everything has to be of sturdy quality too. Epilepsy is also a concern when dealing with LED’s. But, [Jens] project hit the mark, making something that is kid-friendly while at the same time enjoyable for anyone else who likes color-changing lights.

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PS/2 Synth Will Knock You Off Your Broom

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Here’s a hack centered around something a lot of people have sitting around: a PS/2 keyboard. [serdef] turned a Harry Potter-edition PS/2 into a combination synth keyboard and drum machine and has a nice write-up about it on Hackaday.io.

For communication, he tore up a PS/2 to USB cable to get a female mini DIN connector and wired it to the Nano. He’s using a Dreamblaster S1 synth module to generate sounds, and that sits on a synth shield along with the Nano. The synth can be powered from either the USB or a 9-volt.

Keymapping is done with the Teensy PS/2 keyboard library. [serdef] reused a bunch of code from his bicycle drummer project which also employed the Dreamblaster S1. [serdef] is continually adding features to this project, like a pot for resonance control which lets him shape the waveform like an analog synth. He has posted some handy PS/2 integration code, his synth code, and a KiCad schematic. Demo videos are waiting for you across the link.  Continue reading “PS/2 Synth Will Knock You Off Your Broom”

How to Stop Grandma’s Wheelchair If She Goes Out of RC Range

Okay, so he doesn’t have Grandma riding in it that we know of, but [zim] recently decided to turn a Jazzy mobility chair into “a radio-controlled platform for mischief”. RC offers more range than wifi or bluetooth, and he was able to find a reasonably priced secondhand radio on Craigslist. However, he found out that in the event of signal loss, the receiver keeps sending the last commands to the speed controller. [zim] didn’t want his 150 lb (68kg) mischief platform getting loose, so he devised a fail-safe that cuts power to the motor when the signal is lost.

[zim] discovered that the receiver returns channel 3 (the throttle) to a preset condition whenever the signal is lost. He used a 24V HVAC relay controlled by an Arduino Nano to sample the PW on channel 3 and shut it off when either the throttle or the signal are cut.

If Grandma is feisty, you could build this caged-in version with a shopping cart.

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