Quote:
Originally Posted by BrianG
An astable oscillator using a 555 timer IC and a few resistors and caps. A little experimentation may be needed to find the right frequency to satisfy the supply.
or, use just one fan and route the rpm signal so that it also goes to the other fan slot.
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The fans I bought had tach outputs, its just too slow for the PSU to be happy. If the fan work like I think the tach output works then its 2 signals per revolution. If thats the case then the PSU is probably looking for a 16khz signal or something close to that. (fans are 8800rpm)
But since I don't have oscilloscope I have no way of measuring the fans output. They look like normal 3 wire 12v DC fans for PCs though. I will have to look at a 555 circuit.
At this point I may just modify an old tape carrying case. I did a quick test, its so quiet when the lids closed. But I need to drill holes and use fans for circulation. Might work for this weekend, but I don't want to make the box a permanent solution. Will have to look at building a 555 circuit.
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