From: email@example.com (Nico Coesel)
Subject: Re: Quieting all these fan motors
Date: Fri, 13 Sep 2002 17:06:00 GMT
NNTP-Posting-Date: Fri, 13 Sep 2002 16:56:31 +0000 (UTC)
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"George Gonzalez" wrote:
>I'm surrounded by an embarrassment of riches- lots of older
>(1960-1980) test equipment.
>These nice old doohickeys are just right for my relatively modest
>needs-- just enough performance,
>nice big knobs, when they go sick, they're mostlty easily serviced.
>But most of them have one annoying design quirk---
>THEY MAKE A LOT OF NOISE. From their fans, mostly.
>If I turn on the Tek 76xx rack-mount scope, I get a buzzy hiss.
>I usually use the silent 5000-series scope, but if I need more than 2MHz
>of bandwith, I need to power-up the buzzmaster-7000.
>Then I need to check a capacitor labeled "120". Is it 12pf, or 120?
>Only the old HP cap meter can tell, and it adds a more "wooo-wooo" to the
>Then I need to blow up a shorted tantalum in this Tek 475 scope,
>(well, actually, it turns out to have FOUR shorted caps), so I need
>to turn on the 0-40V, 0-10Amp power supply. It adds a rattly hiss to the
>On rare occasions I need to also measure a frequency to many digits,
>so I turn on the 5360A computing counter. I don't begrudge it having a big
>fan, as it must contain 300+ TTL IC's (and not LS TTL either). But that fan
>would blow off my soon-to-be-needed toupee, it's just too much to stand for
>any length of time.
>I'll soon be trying to resuscitate a PDP-8/E, which IIRC has at least three
>Any one of those fans, I could stand for a short time, but all of them is a
>I can try concentrating on a fuzzy schematic, but with my disposition,
>as much as I try to ignore them, after about 30 seconds, I want to yell
>"QQUUUIEEETTT!!!". Not that it would help, but it sure makes me feel
>Turning them off is one obvious option, but I hate putting these older
>thingys thru any unnecessary power and thermal cycles. What to do?
>I see that a lot of new PC power supplies have a simple thermistor
>the little 12VDC fan in there. Is there a source for these thermistors?
>How amenable are they to controlling your basic 1/100th HP shaded-pole
I think it's a good idea to replace the fans by more quite types.
Quiet fans from PAPST are easy to buy over here. It's going to be
expensive, but it's probably worth the trouble.
Having the fans run at lower speeds may harm your equipment. More heat
means shorter lifetime.
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