Author: Steven A. Cholewiak

Website Host Transfer Complete + Sparks

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I’ve completed the server move and the DNS changes, so hopefully everything will now work. There was a problem with the email program (cgiemail) during the transfer, but it seems as though I resolved the problem by using a different script (FormMail). Please feel free to send me an email or leave a comment in this post if there are any problems.

High Voltage Sparks Over and Through Red LED 2/3

As an added bonus, I’ve attached some pictures of sparks generated with my high voltage power supply, which I was able to fix. It appears as though the old MOSFET had blown, so I was able to recreate the circuit with no issues. Continue to the post for a few more pictures. Read More

Changing Website Hosts

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For the past two years I’ve hosted my website using QualityHostOnline and the traffic to my website and bandwidth usage has steadily increased every month. I’m very happy about this, but unfortunately this month I’m afraid I might go over my alloted bandwidth of 2 GB.

I’ve decided to change my website hosting to a higher bandwidth host (AN Hosting) as a long term solution. Hopefully there won’t be any issues, but please let me know if there are!  I highly recommend QualityHostOnline as a very affordable host for small websites needing <2 GB of bandwidth each month; I’ve never had any serious problems that have not been solved by their support staff within 24 hours.  I’ll let you know how AN Hosting turns out.

Royal Blue Luxeon K2

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Royal Blue Luexon K2Lowe’s had a 1 Watt Luxeon Plastic Flashlight on sale for $2.50 recently. I ordered one online for in-store pickup and was able to get one of the last flashlights available at the store closest to me (they actually didn’t have enough to fulfill all of the orders, but I was able to convince them that I deserved one). When I brought it home and broke it open I found a nice white 1 watt Luxeon star hex (LXHL-MW1D) bolted to the top. The flashlight itself felt relatively cheap and flimsy, so I decided to find out what I would do with it and how I could modify it. The flashlight used 3 1.5V AA batteries in series (i.e. 4.5V open circuit) and had a 1 Ohm resistor in series to limit the current to the LED. White flashlights are nice, but sometimes you need to just have fun. So, I took one of the Luxeon K2 Royal Blue LEDs (LXK2-PR12-L00) that I had purchased with Matt Kocsis and dropped it in. Read More

Updated Resume

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I’ve updated my resume web page to include information about a conference paper that I co-authored with Dr. Hong Z. Tan at the Haptic Interface Research Laboratory (HIRL), where I have been working for the past semester:

Cholewiak, S., & Tan, H.Z. (In Press). Frequency analysis of the detectability of virtual haptic gratings. Proceedings of the 2007 World Haptics Conference. Tsukuba, Japan: WHC.

I have also included information about published papers and presentations in which I have been acknowledged.

Added Translation Plugin

Steven A. Cholewiak 4 Comments

I’ve added the WordPress Global Translator Plugin to Semifluid.com, so now anyone can easily translate my English blog posts to:

  • French (Français)
  • Italian (Italiano)
  • German (Deutsch)
  • Portuguese (Portuguese)
  • Spanish (Español)
  • Japanese (日本語)
  • Korean (한국어)
  • Chinese (汉语)

You should see (and use!) the translation links at the top of every page in the upper-right hand corner. Please let me know if there are any problems or issues.

Update (01/23/2007)

Unfortunately I’ve had to disable the Global Translator Plugin because it has been having some compatibility problems. Hopefully I’ll be able to update the plugin soon.

Some More High Voltage Videos

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Last night a number of events conspired against me and my geeky endeavors:

  1. My flyback transformer driver was working intermittently for a period of time then suddenly stopped working. It seems as though there is a problem with either the 7805 or the PIC12F683, but I can’t pinpoint the problem because of events 2 and 3 below. I’ll have to double check to make sure that I didn’t accidentally fry any components with, ironically, static discharge.
  2. My multimeter was accidentally left on the last time I used it, so the batteries were dead and I couldn’t check the voltages at different points in the circuit (to determine whether the PIC was switching the driver MOSFET). Why does this always happen at the most inopportune times?
  3. My PIC programmer is no longer recognizing any of my PICs. I’m hoping that there’s just a problem with the firmware and that I can fix it by borrowing a friend’s programmer to reflash it, but nothing I could do last night would make the programmer recognize PIC12F675s, PIC12F683s, or PIC16F628s. Maybe this is a sign that I should get an ICD2…

So, in short, it was an overall crappy night. So, here are some of the latest videos with the high voltage flyback transformer zapping some more beer, rum, and just plain arcing just for the heck of it. I’m heading back home tomorrow for Thanksgiving tomorrow, so I won’t be able to debug the problems until I get back. Read More

Luxeon K2 LED show-off

Steven A. Cholewiak 15 Comments

A friend (Matt Kocsis) and I purchased some Luxeon K2 LED emitters from Lumileds and I’m looking forward to building some constant current PWM drivers for them. I’ve found a couple of constant current driver schematics, but I’m planning on pulsing the outputs (which can draw up to 1.5A), so I want to make sure that the circuits will work with the high-frequency PWM. Matt and I are also working on a heatsink that will effectively cool these LEDs. The plan is to create a programmable high-intensity RGB spot/wash light with pan/tilt and optic (i.e. focus) control. We’ll see how this project pans out, but in the meantime, playing with these incredibly high intensity LEDs has been quite fun. Read More

PIC12F683 High Voltage Flyback Transformer Driver

Steven A. Cholewiak 25 Comments

PIC12F683 High Voltage Flyback Transformer DriverA friend at Purdue University (Sumanth Peddamatham) helped motivate and inspire me to create a high voltage flyback transformer driver for a computer CRT flyback transformer. While the schematic and code for driving the transformer are extremely straightforward and simple, finding and obtaining a high quality solid state flyback transformer can be difficult. Please note that the voltages generated by the flyback transformer are potentially very dangerous, so extreme care must be exercised when building and/or using the schematic presented in this project. Diode split flyback transformers (like the one used in this project) can output 25kV or more. Read More