Lately I've been elbows-deep in some broken Playstation 3's and found myself wanting to test their cooling fans. These have a three-wire header with leads colored brown, black, and gray; you may be tempted to conclude that this is a brushed DC fan with a tachometer lead, but you'd be wrong. These are brushless fans, and the third wire is a PWM signal that you supply to control the speed of the fan. The two PS3s (both “fat” style) I've opened recently have compatible fans from separate manufacturers; one is a Nidec G14T12BS2AF-56J14 and the other is a Delta Electronics KFB-1412H.

Nidec and Delta models

It's not trivially easy to find datasheets for these fans, but no matter. If you just want to test them or need a good centrifugal blower for one of your own projects, do the following:

• Apply 12 volts across the brown and black leads; +12 V on brown with return on black. The fan will probably jump a little but it won't start spinning.
• Drive the gray lead with a TTL-level pulse train at 25 kHz from a signal generator or 555 timer circuit or microcontroller or whatever.
• Control the duty cycle of this pulse train to adjust the speed.

That's it!

I withdraw my endorsement of Audio-Technica's ATH-ANC1 headphones.

Fatigue failure of first one, then the other earphone support

Barely a year after I bought and first wrote about them, one earphone broke free from the headband; when I temporarily fixed this with electrical tape I was rewarded with about two weeks of additional service before the other earphone failed in exactly the same way. More galling than Audio-Technica's lack of attention to fatigue design, however, was their lack of attention to customer service—representatives of the company refused to make any replacement parts available and, since I was just outside of the warranty period, insisted I send them my headphones and pay more than half the price of a new unit to have them repaired. Nonsense!

Instead of dealing with Audio-Technica anymore, I took this as an opportunity to try out a technique I read about in Make magazine: fixing delicate plastic parts, such as the broken bridge of an eyeglass frame, by wrapping the joint with thread and coating it in epoxy, making a kind of thread-reinforced composite.