SPCR Power Supply Test Rig, v.4 (and v.4.1)

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Extech AC power analyzer, ATX PSU and 0~140VAC 3KVA variac.
The last item weighs 16 kg, by the way.

  • Ling Bridge TDFC 2J-3 Variac rated for 120VAC / 20A input and 0~140V output. The internal rating is for 3KVA. (See orange colored device above.) (new for V4 PSU test system)
  • Bruel & Kjaer (B&K) model 2203 sound level meter. This professional caliber SLM is >20 years old, weighs over 10 pounds, and is completely analog in design. It has a dynamic range that spans 140 dB. The unit can measure accurately down to about 16 dBA. A quiet environment is a prerequisite to low noise testing; the lab has been measured down to ~17 dBA at night, and a <16 dBA adjacent room is also available for any PSUs that are quieter.

B&K model 2203 sound level meter measures down to ~16 dBA.

  • High resolution audio recording system consisting of a modified silent Shuttle Zen PC, M-Audio Tampa digital mic preamp, M-Audio FireWire 410 external digital sound interface and a Sennheiser ME 66 shotgun microphone. Recordings of the sound of the PSU are made at selected power levels from 1m and 30cm distance at 24bit/88kHz, then converted to a high quality MP3 for readers to listen and compare. All the MP3 sound files posted on SPCR since early July 2006 have been recorded the same way with the same equipment for relevant listening comparisons.

Audio recording system: Modified Shuttle Zen PC running a P4-2.53 and suspended Samsung 40G 2.5" notebook hard drive. This PC is virtually inaudible and measures less than 17 [email protected] SPL. A single channel M-Audio Tampa mic preamp with 96-kHz / 24-bit A/D converter and M-Audio Firewire 410 external digital sound interface feed the signal from the microphone.

Sennheiser ME 66 shotgun microphone has extremely low internal noise, which allows recordings to be made from a meter away even with very quiet sounds. The 1m recordings capture "nominal" volume, audibility, and sound character; the 30cm recordings capture all the details from even the quietest noise sources.
  • Dedicated 120 / 240 VAC Power Source (new for V4 PSU test system)
    The PSU test rig is in a room that used to be a kitchen. In fact, there is a 120/240V high-current AC outlet for an electric stove/oven directly behind the cabinet on which the PSU test loader rests. This dedicated outlet runs directly off two 15A/120V circuit breakers in the main electrical panel. This feature makes it ideal for use as a dedicated high power PSU test AC line. We obtained a 240V/15A power cord for use with this outlet, then ran the leads to two paired utility AC outlets, one pair for 240VAC and the other pair for 120VAC.

The dedicated heavy-duty 240VAC appliance outlet and plug. A standard Canada/US 120VAC plug is dwarfed in comparison.

The dedicated 240VAC and 120VAC outlets are only for PSU testing; this circuit does not feed any other electrical devices. The Extech 380803 Power Analyzer / Data logger in the background has no trouble with 240VAC, which is run through the unit. The LED display shows that 244VAC is at the input. Extech MultiMaster 560 True RMS Multimeter and DBS-2100 PSU load tester can be seen in the foreground.

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SPCR Articles of Related Interest

SPCR's PSU Test Platform V.3 (Sept 2005)
Corrected Efficiency Results for Recommended PSUs (Oct 2005)
Audio Recording Methods Revised (July 2006)
SPCR's Revised PSU Testing System (March 2004)
Power Supply Fundamentals and Recommendations

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POSTSCRIPT, Dec 22, 2006: Bonefish - Version 4.1?

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