Reply-To: "George Gonzalez"
From: "George Gonzalez"
Subject: Quieting all these fan motors
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
NNTP-Posting-Date: Fri, 13 Sep 2002 16:21:37 GMT
Organization: AT&T Broadband
Date: Fri, 13 Sep 2002 16:21:37 GMT
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
Any hints appreciated.