Product Review: CP06 low-cost AC/DC clamp-on current probe

I bought this bargain basement clamp-on current probe on eBay. It doesn't even seem to have a manufacturer (shamed out of existence?), but the model number is CP06. It's $70 shipped, and is probably worth it, especially if you plan to measure DC and 50/60Hz AC waveforms. It will not do high-frequency measurements. The DC accuracy seems good enough for many different applications where cutting into the test wire is not preferable.

Note: Hold down the "zero" button for a couple seconds, then release.

Transcranial Magnetic Stimulation project - part 1

Transcranial Magnetic Stimulation (TMS) is a technique to stimulate brain tissue directly through the skull. It works by sending a very high current pulse through a coil that is located on the subject's scalp. The fast-rising edge of the pulse induces a current in the brain tissue, causing neuron stimulation.





This device uses a capacitor bank, high current SCR, trigger circuit, figure-8 (or butterfly) coil, and high voltage charging circuit.

Link to the SCR datasheet: http://www.5scomponents.com/pdf/5STH_30J4501.pdf

Some good technical information: http://www.abovesobelow.com/TMS/cTMS.pdf

Wikipedia: http://en.wikipedia.org/wiki/Transcranial_magnetic_stimulation

Extech IR250 infrared thermometer disassembly and plans for thermal imaging

One of my ongoing projects is to develop a low-cost thermal imaging camera. In this video, I take apart an Extech IR250 infrared thermometer with the intention of grabbing an analog or digital signal so that I can record temperature measurements while using a scanning or image processing device to select portions of the scene being examined. Unfortunately, it looks like the analog circuitry is completely sealed inside a custom IC that is hidden under a blob of potting material. I'll remove the IR sensor from the board and build my own analog amplification and digitization hardware.






Common digital output IR thermometer sensor:
http://www.melexis.com/Infrared-Thermometer-Sensors/Infrared-Thermometer-Sensors/MLX90614-615.aspx

TPS334 sensor datasheet:
http://www.datasheetcatalog.org/datasheet/perkinelmer/TPS334.pdf

Analog Devices app note regarding thermopile sensors:
http://www.analog.com/en/all-operational-amplifiers-op-amps/operational-amplifiers-op-amps/products/technical-articles/using_thermopile_sensor_in_ir_digital_thermometers/resources/fca.html


Servo pan/tilt IR imaging scanner project:
http://www.cheap-thermocam.tk/

Redshift thermal imaging:
http://redshiftsystems.com/site

What should I build with six ultracapacitors?

I bought six 2600F 2.5V ultracapacitors from Electronic Goldmine. They were on sale a couple weeks ago, and this was one of my rare impulse purchases. I am thinking of building a portable capacitive discharge welder, or perhaps conventional spot welder. What are your ideas?

Lavalier microphone comparison: Audio-Technica ATR-3350 vs Sony ECM-55B

My first youtube videos were made with my camera's on-board stereo microphone. The camera is a Lumix GH1, and the mics are fairly good as far as prosumer video DSLR cameras go. One problem is that the camera's automatic gain control cannot be turned off, and having unexpected gain changes during an audio recording is not preferable. Another problem is that the audio preamplifiers in the camera are somewhat noisy, and lead to a lot of hiss (high noise floor) in the recording. Finally, it's impossible to get good sound when the microphone is positioned far away from the sound source when room tone and echoes are present. The solution to all of these problems is to make use of a lavalier or lapel microphone and use a low-noise dedicated recording device. I use a Zoom Handy H4 recorder. The H4's on-board mics are really nice, but it is still preferable to have a microphone very close to the subject's mouth to capture detailed, high-quality sound.

I started using an Audio Technica ATR-3350, which is only $20 or $30 new, and the mic is OK, but has very little high-frequency response. This can be corrected with equalizer settings in post-production fairly well. I recently upgraded to a Sony ECM-55B, which sounds better, but I am not sure it was worth the expense. I was really expecting the mic to have a much higher output level than the ATR-3350, thus allowing me to turn down the gain on my recorder and have a much lower noise floor. As it happens, the mic requires even more gain than the ATR-3350. Overall, I am pretty satisfied with my sound recording setup -- the only addition I might make is a low-noise preamp to try boosting the lavalier mic signal while adding less noise than the H4 adds during the high pre-amp gain stage.