We are slowly and painfully making progress with learning to fly our 3D Printed Mini Quadcopters. Cliff has helped us out with some tweaks & balances. Hopefully some more members will be interested in building their own, and will help add to the swarm.

Recently Ben, Cliff and Claudio have built Diametric’s Mini Quadcopter. We met a fellow RepRap user- Diametric- at this years Midwest RepRap Festival in Elkhart Indiana. He brought along a 3D printed quadcopter that he designed and built.

The quadcopters are remarkably inexpensive, the design, models and bill of materials can be found on Thingiverse. They are easy to build and easy to get off the ground. We’re still learning how to fly them however. While all three have taken flight, we have had some accidents and damaged the frames on 2 of them, twice. We’re not too worried when that happens, for we can always reprint the frame within about an hour and a half on one of our 3D printers.

Building the quadcopters

Claudio’s Quadcopter

Cliff’s Quadcopter

Claudio’s Second Quadcopter

Ben’s Second Quadcopter

Ben’s Quadcopter- We are still learning…

Here are a couple of videos Dru made to show off the progress of his bubble bot.

Ever since the Palm Pre came out I’ve been in love with it’s inductive charging upgrade. Similarly to the Powermats, the charging base acts as a device stand with it’s integrated magnets in addition to charging your device without having to plug and unplug your device every time you need to use it. Once on the charger it outputs 5.50v. It’s a bit higher than other USB chargers I’ve used.

Inductive charging back with base

“Induction chargers typically use an induction coil to create an alternating electromagnetic field from within a charging base station, and a second induction coil in the portable device takes power from the electromagnetic field and converts it back into electrical current to charge the battery. The two induction coils in proximity combine to form an electrical transformer.” -Wikipedia

After peeling off part of the backing you can see the coil and it’s output circuitry. You can also see the four magnets it uses to attach itself to the charging base. They do a good job of holding my heavy phone and case to the base.

After finally getting in the Touchstone base and replacement back I decided to get this working over some lunch. I was a bit uncertain at the time that the magnets would be able to hold my phone while it’s in it’s case. I also wanted to make sure that I wouldn’t experience any signal loss issues or suffer from any overheating while charging. I found the quickest way to make this work was to take the male end of a microUSB plug and wire it directly into the contacts off the inductive back. After taking apart the microUSB plug from a spare dead cable, you can use a 200 ohm resistor to short the D+ and D- pins on the plug. This allows the device to charge at a higher current, which will in turn charge a bit faster. After soldering it up I used some colored silicone to insulate the back of the plug.

Roughed in and adjusted the case to improve clearance

It works!

In order to clean this up and make it a bit more permanent and presentable, I have get away from using the charge port and get it through the housing. Unfortunately, the back housing of my phone has a nice metal frame right where I want to mount it. There are also a few antennas I need to avoid. The induction coil is going to have to stay on the back of the case, and somehow get passed thorough the metal housing into the board. I drilled through the back of the case near the sim card holder.

It took a bit of poking and prodding but I was able to find 2 test points that when the motherboard was plugged into a USB charger had +5v showing between the points and the ground plane. No magic smoke was released!

After a bit of soldering I was able to route the positive lead out of the phone housing and is now staged for the next step- going through the housing and into the case. The metal frame of the sim card holder is attached to the ground, so I can use that to complete the circuit. On a normal USB type charge port the ground pin attaches to the ground plane which is usually where all the shields are anchored into so I feel safe doing the same.

For the next stage of the project I’ll have to use some contacts or pogo plugs embedded within some silicone to go from the inside of the phone to the contact points on the induction charger. Ben had the good idea of using some thin copper prototyping board to act as thin traces.

To be continued!

Recently Roy and I set out to build set out to build a better headphone amplifier for our higher end Sennheiser headphones. A headphone amp simply boosts the power to the headphones a bit, this results in better sound on the bigger headphones. The design is built around a know design over at Diy Audio Projects. It is a Class A amplifier with a 12AU7 tube. We ended up puting a spin on the project and added a PCM2704 USB DAC (sound card). Sweet glowing tube action pictures are below.

Populating the board

Fully Populated

All soldered up.

Back of Amp

Front of Amp

Amplifier board hung.

Blown apart

Amp Running