Lamptron FC-2 Rheobus Fan Controller
While digital fan controllers can often be 'tested' for their ease of use, temperature reading accuracy and built-in safety features, the Lamptron FC-2 being entirely manual in its operation cannot be subjected to the same level of testing. However as Lamptron have said themselves, the FC-2 is all about being able to control high-powered Delta fans, and it just so happens that we've got knocking about the office.
But before we start creating our own Delta powered wind tunnel we're going to be checking the voltage output of the FC-2 fan headers with each of the controller turned fully to the left (off) and fully to the right (100%). The reason behind this testing is that some fan controllers fail to provide the maximum voltage to the fans (12v) when set to 100% or fail to completely power off the fans when set to 0%.
Referring back to the specifications for the FC-2, Lamptron state that the power output is adjustable between 0v-12v. However as we can see from above, with each of the controller knobs turned completely to the left, the fan controller still outputs varying levels of voltage to each of the headers. This unfortunately poses a problem in that fans which are able to run on voltages as low as 3.9v will still be turning, while fans connected to other headers running voltages around 1.9v wont.
Once the knobs are turned fully to the right the voltages even out significantly. At this point the voltage INPUT from the PSU is 12.20v, showing that there is very little loss of power in the FC-2 circuitry when running at 100%.
Delta Fan Test
For this stage of the testing we started off by connecting a single Delta TFB1212GHE to one of the fan headers. Rated at 2.45a (39w) the fan comes quite close to the maximum output power of a single header on the FC-2. With the rheobus knob turned fully to the right (100%) the fan worked as expected. However, on trying to slow the fan down at all by turning the knob to the left, the fan entered a constant speed up > slow down cycle accompanied by a high pitched squealing. Initially we put this down to being an issue with the fan not wanting to operate at anything less than 12.0v, but after replacing the FC-2 with a large 50w rheostat, the fan acted as expected thus placing the blame directly on the FC-2 controller.
Not deterred by this incompatibility we switched the single TFB1212GHE out for six Delta FFB1212EHE's rated at 2a (24w) each. Once again, at anything other than full speed the fans would enter a speed up > slow down cycle but thankfully this time there was no high pitched squealing.
This anomaly can most likely be put down to the use of PWM circuitary in the FC-2 which sends pulses of voltage to the fans in order to run them at slower speeds. Unfortunately this also renders the Delta fans we chose unusable at anything other than 100%. A recording of the fans can be heard here. However due to the 50dba+ rating of the fans the quality of the recoding isn't too good.