KT88-1016 EEG Drivers for BioEra

April 8, 2012

KT88-1016 is a 16 channel EEG device produced by Contec Medical Systems in China and is currently one of the most affordable (per channel) EEG machine.

KT88-1016

On the plus side it has 16 channels allowing for (almost) full 10-20 EEG/qEEG recording, multi-channel neurofeedback training, or brain machine interface research. It comes ready to use with contacts, electrodes and rubber mesh cap. On the minus side it lacks 3 center channels (Fz Cz Pz) to do a standard EEG/qEEG recording, sample rate is 100 sps which is lower relative to industry standard, rubber mesh cap is hard to use and from what i read the software is outdated. However despite the shortcomings this device became popular among the eeg and bmi enthusiasts due to the good price relative to the number of channels you get.

The main challenge to overcome in using this device is to get your favorite eeg/bmi/neurofeedback software to talk to it. Thanks to the efforts of Alexandra Elbakyan and others the serial protocol used by device was cracked and several programs that read data from KT88 have been posted on yahoo’s contect88 board. Alexandra also posted an OpenViBE driver however stopped any further development since.

Taking these efforts one step further i wrote a driver for popular BioEra software which can be downloaded from here as well as from contect88 board files section. I have included source code which you are free to use and modify.

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Dead HVAC fan repair

September 2, 2011

Couple of weeks ago, upon returning home from a short trip we found our house much too warm and after quick inspection found that central AC was not working. First suspecting blown fuse i went downstairs hoping for a quick resolution. Alas that was not the case. Furnace (serving as the blower) had power and AC was working as i could hear fan outside as well as the coolant running through the pipes.

After opening up the furnace i found a board with blinking lights repeating pattern 3 green 1 orange and infrequently changing to 3 green 3 orange. These codes translated to blower motor not running at the right speed or not running at all. Starting a search for the solution on the net I’ve stumbled on this long thread which suggested that this might be due to a failed thermistor and that repair could be as simple as replacing it. Taking the power supply off the motor i was happy to find a charred and broken apart thermistor.

The part number was SG348 and after further research i found that this was a Inrush Current Limiter – a thermistor with negative temperature coefficient (NTC) which means that it’s resistance decreases as it gets hotter.  The primary purpose of it is to limit starting current in motors and transformers. This particular ICL thermistor has a resistance of 1 Ohm when it’s cold and can sustain 20 Watt of power. It was made by RTI Electronics under the brand name of SURGE-GARD and was often used in GE motors. The SG348 is not longer in production, but SG100/SG301 can be used instead. In fact any NTC thermistor with room temperature resistance of 1Ohm and 20A maximum current (or 1Ohm*20A=20Watt maximum power). In fact  DigiKey had 3 parts satisfying that requirement with 570-1041-ND being the cheapest at $1.77

Finding the replacement part was easy – finding it locally proved impossible. So after calling all of the local electronics stores I had no choice but to order from DigiKey and wait for the part to arrive. In the mean while i started looking for a work-around. Some people on the forum suggested short-circuiting contacts where thermistor was but i found it too risky. I decided to place a fixed resistor in place, however finding one that would not melt down at 20A was also not easy. Luckily, a local Radio Shack still had some memories of it’s former glory and carried 1 Ohm 10W resistors. Putting them in parallel to distribute the load i had a temporary work around:

 

Workaround using Radio Shack's 1Ohm 10W power resistor

 

This solution was a better alternative to the short-circuit however it reduced the efficiency of the fan essentially by wasting energy in the resistor all the time rather than only during startup as in case of a ICL thermistor. The picture above is after fan has been working for a week or so and you can see those resistors heated up quite considerably and even melted down part of a rectifier nearby. There was also a discoloration on the end of one of the resistors.  so i can certainly can’t call it a perfect solution but it worked for me.

Here’s how the power supply looked like with the replacement parts in place:

Replacement Inrush Current Limiting Thermistor in place

 

At the end, the most impressive part for me was the power internet allowing free peer to peer sharing of knowledge. I was pleasantly surprised how easy it was to find this knowledge on the net and how valuable it was – was I call a HVAC technician it would cost me several hundred dollars in replacement power supply or even entire motor.

 

My try at knife making

August 13, 2011

One winter evening, I had a discussion with my dad dealing with hunting and woodworking knives and the steels that make them. As a result of that discussion, I realized that my knowledge of metallurgy doesn’t go beyond “smelt iron with carbon and you get steel”. I decided to look into understanding different steels and what makes one better than other, which lead to steel composition, which led to heat treatment process, which led to a variety of topics, such as; blacksmithing, knife grinding, heat furnaces, oxidation protection, Japanese blades, sanding/grinding machines, edge geometry, sharpening, etching, and so on. While this was a fascinating intellectual trip, it also made me want to get my hands dirty and actually make something.

I decided to start small and make a couple of pairing knives using stock removal method:

#1 Front

#1 Back

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Simple Wheel Balancing Jig

June 13, 2011

I was recently changing tires on my band saw and needed to balance the wheels. I have heard of the method where you spin the wheel and whichever side ends up down the most time is the heaviest, but i wanted a little more precision. After several failed attempts to use a spinning-top kind of a device i came up with (and i don’t claim originality) with following simple device:

Wheel Balancing Jig


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Re: My take on your Mak Board

March 9, 2011

From: Brian Dubberley, brian@inventive-solutions.ca

Hey Aleksey,

See attached photos.

I recently built & installed your makiwara assembly in our aikido dojo to help us learn to punch more authentically. Since I had to anchor it to a cement block wall, I decided that using screws to anchor the boards might not be strong enough. Instead I used stove bolts which you can see in the photo where I removed the cover plate. Basically, the wall board is screwed into the masonry anchors (#12 x 2.5″ screws) after first inserting the stove bolts so they face outwards. BTW, drilling masonry requires patience and knowledge that if you hit something stronger than the bit, just drill another hole. Then each spacer board and the striking board assembly are jiggled onto the bolts which are then tightened with the nuts and thereby secure all boards as one unit. The cover plate just protects the users legs from the ends of the bolts and it looks nicer.

I also DS taped an old Microsoft mouse pad and then stapled some scrap leather to the top of the striking board instead of the traditional sisal. So far, sensei skinned his knuckles on the leather already, and I loaned him my daddy’s old bag gloves, but my hands are tougher than his and the leather seems just right as long as I strike properly.

I built your project because our sensei commented that it would be cool to have, but also because I want to build your accelerometer to get me back into electronics. Thanks for taking the time to document this project. Yes, you may post the pix and these comments.

Cheers,

Brian Dubberley

MSP430 USB Stick Development Tool (EZ430-F2013) – JTag breakout cable

September 26, 2010

For my next project i decided to try TI low power microcontrollers and for that purpose acquired a $20 development tool: EZ430-F2013 (doc, digikey):

eZ430-F2013 development tool

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HMC5843 (3-Axis Digital Compass) Breakout

September 26, 2010

In my recent project i have been playing with the HMC5843 digital compass ic and not wanting to spend $50 for a $20 part and also to challenge myself i’ve decided to build my own breakout board. Here’s the end result and the HMC5843 Breakout etch positive if you want to do it yourself:

This image is saved at 300 dpi

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Punch Acceleration Sensor – Follow Up

April 26, 2010

Couple of questions came up as a result of my post and so after some additional measurements and thoughts, here’s the follow up:

Noise

I have measured the output of ADXL193 accelerometer with the Digital Storage Oscilloscope so here’s how it looks through time as read at the sensor location:

ADXL193 output during AD conversion

AD conversion frequency

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Teardown: Swann Night Hawk Wireless Security Camera

April 20, 2010

I have recently acquired several broken Swann Night Hawk SW231-WOC wireless security cameras and figured i would document the tear down process and anything interesting i might find. My goal in this project was to satisfy my curiosity, try my hands at fixing them and perhaps even learn something in the process.

Here’s how it starts:

Swann Night Hawk Camera

And here is how it ends:

Swann Night Hawk Camera - Teardown

Swann Night Hawk Camera - Teardown

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Dirt Cheap Light Tent

April 11, 2010

After making photos of my previous project i was disappointed with the way they came out – wooden grain background and lighting from the table lamp just weren’t good. So i started looking into Light Domes and Tents. A lot of the items i liked were out of stock which made me wander – just how bad would be the diy solution using cardboard box? Well, it turns out not too bad at all. Here’s tent/box:

DIY Cardboard Lighting Tent

DIY Cardboard Lighting Tent - back

DIY Cardboard Lighting Tent - inside

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