phil@amdcad.AMD.COM (Phil Ngai) (01/05/88)
I see that Rotron now has a great idea in fans. It's a DC operated fan with an extra two wires. The resistance you provide between the wires determines the speed of the fan, with the intention being that you use a thermistor to regulate the amount of air moved based on the temperature. The power supply voltage is not a factor (within limits of course). This is all done with PWM type stuff so that efficiency is very high. I hope Apple takes note of this! -- "how long will the machine be down?" "as long as you stand there and bother me" Phil Ngai, {ucbvax,decwrl,allegra}!amdcad!phil or amdcad!phil@decwrl.dec.com
wtm@neoucom.UUCP (Bill Mayhew) (01/07/88)
My Tektronix 2445 'scope that I got 3 years ago has a fan whose speed varies. What is also a neat benefit is that it makes it easier to maintain a semblance of *constant* rather than some arbitrarily low temperature. Quite a good thing for analog things that drift in calibration with respect to temperature. That scope has taken some remarkably rough treatment and stays quite stable. I agree; Apple should have learned about fans in, say about 1979 or so. I've replaced more Apple power packs in machines here than I like to think about. You'd at least think they could have put some ventillation slots in those chintzy Apple ][ power packs. I suppose their lawyers advised them to seal the power pack to prevent some kid from probing it with a paperclip or whatever. Those Kensington System saver aftermarket fans help some, but there still isn't any air circulation inside the power pack.