Gregory T. Nojeim, Senior Counsel at the Center for Democracy & Technology (CDT), answers viewers’ questions on government surveillance for the “Ask CDT” series. To see the full list of questions and answers, visit cdt.org
13
Feb 11
$ 3 Harbor Freight Multimeter vs. supply voltage. Who wins?
So, it's been said that with a cheap multimeter to AC voltage lead to blow up in your hands, and who deserves Darwin striking. Let's see if this is really true, what with pretty much the cheapest meter out there. The list price is U.S. $ 5, but they are always on sale for less, you can usually get them for $ 2-3. The test is simple. Harbor Freight multimeter. Mains. Plug it in. Is it blow up? The meter in question www.harborfreight.com
01
Jan 11
R6A2 Arctic Cooling F12 PWM
Same as the previous round 6A tests except I swapped around the amp/volts meters and replaced the centech amperage meter with a Radioshack meter that can read milliamps. Meter Arrangement from Left to Right to Bottom: Air Flow Velocity in Feet Per Minute (Blue Extech) Noise Level in dbA (Grey ART) Voltage in Volts (Red Centech) Current in Milliamps (Grey/black Radioshack) Speed of Fan in Hz (Grey Mastech) RPM = Hz x 30 Approximate Speed (Bottom Scythe Display) +- 50RPM reads a little highStarting in on a much larger round of tests, this time with almost all new testing equipment that should be a big improvement over my previous work. Mainly, my old anemometer made noise and it also seemed to interact and create odd results with some fans. I’ve switched that out to an Extech Hotwire anemometer which has no vane, I’ve also switched over to an American Recording Technologies A-weighted sound level meter which is much more matching of the human ear’s perception of noise level. Finally I’ve switched to a Swiftech MCR120 for a wider and lower air pressure drop. In addition I’ve added back in the Scythe meter for approximate RPM +-50RPM or so, and using my old Mastech meter for monitoring Hz on the RPM wire for a more exact RPM (Hz x 30 =RPM). Anyhow, that’s it, planning to do a bigger round this time, but in smaller 6-10 fans at a time. Testing Notes: -Air Flow: Extech Heavy Duty Hot Wire, permanently fixed to outlet chamber 3.66″ ID port. (Good down to 40 FPM) CFM is …
20
Nov 10
R6A2-ScytheUltraKaze2000.wmv
Same as the previous round 6A tests except I swapped around the amp/volts meters and replaced the centech amperage meter with a Radioshack meter that can read milliamps. Meter Arrangement from Left to Right to Bottom: Air Flow Velocity in Feet Per Minute (Blue Extech) Noise Level in dbA (Grey ART) Voltage in Volts (Red Centech) Current in Milliamps (Grey/black Radioshack) Speed of Fan in Hz (Grey Mastech) RPM = Hz x 30 Approximate Speed (Bottom Scythe Display) +- 50RPM reads a little highStarting in on a much larger round of tests, this time with almost all new testing equipment that should be a big improvement over my previous work. Mainly, my old anemometer made noise and it also seemed to interact and create odd results with some fans. I’ve switched that out to an Extech Hotwire anemometer which has no vane, I’ve also switched over to an American Recording Technologies A-weighted sound level meter which is much more matching of the human ear’s perception of noise level. Finally I’ve switched to a Swiftech MCR120 for a wider and lower air pressure drop. In addition I’ve added back in the Scythe meter for approximate RPM +-50RPM or so, and using my old Mastech meter for monitoring Hz on the RPM wire for a more exact RPM (Hz x 30 =RPM). Anyhow, that’s it, planning to do a bigger round this time, but in smaller 6-10 fans at a time. Testing Notes: -Air Flow: Extech Heavy Duty Hot Wire, permanently fixed to outlet chamber 3.66″ ID port. (Good down to 40 FPM) CFM is …
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