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Hey guys - Ok, so I'm using a brushless 12vDC fan driven directly with 12v from a 12v, 1.5A regulator. Now, a while back, this circuit was working fine - no dramas at all. But then, one day I accidentally broke the lead of the original 12v regulator which the fan uses. No biggie - just replace the thing, right? Apparently not.
You see, I did and here's what happenes. The fan starts up at full power and works fine for about 1-2 minutes. Then, it switches off, tries to start itself (but fails) a few times, comes back to life then dies again. Each on-off cycle bit lasts about 30-40sec.
Hmmm... So I replaced the regulator. And the same thing happened again. Perplexed, i put my scope on the fan positive line and visually saw the voltage rise and fall like I described earlier. Next I tested stuff. The regulator regualtes fine (both under a recent test and under past use), the fan works on a different 12v line (from the same power supply) and wiring should be Ok. The device normally gets warm (is heatsunk) but during this problem it was a little hotter. The shutdown temp of the reg is 150 C - and the max temperature (incl headroom) found was 70C. So this doesnt appear to be the problem either.
I attached a video here to show the voltage fluctuation - the fan starts up when the line on the scope transitions from high-to-low.
What have i done this time???![Confused :confused: :confused:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
You see, I did and here's what happenes. The fan starts up at full power and works fine for about 1-2 minutes. Then, it switches off, tries to start itself (but fails) a few times, comes back to life then dies again. Each on-off cycle bit lasts about 30-40sec.
Hmmm... So I replaced the regulator. And the same thing happened again. Perplexed, i put my scope on the fan positive line and visually saw the voltage rise and fall like I described earlier. Next I tested stuff. The regulator regualtes fine (both under a recent test and under past use), the fan works on a different 12v line (from the same power supply) and wiring should be Ok. The device normally gets warm (is heatsunk) but during this problem it was a little hotter. The shutdown temp of the reg is 150 C - and the max temperature (incl headroom) found was 70C. So this doesnt appear to be the problem either.
I attached a video here to show the voltage fluctuation - the fan starts up when the line on the scope transitions from high-to-low.
What have i done this time???
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