Typically a silicon diode has about 0.7 volt drop per unit. Thus two diodes
in series would drop 1.4V and three in series would drop 2.1 volts etc. The
advantage of using a diode over using a R has to do with constant voltage
drop using a diode where a fixed R will have different voltage drop values
depending on current demands. Some fans may have a higher starting current
than running current. With a critical value of R one could experience a
condition where the fan won't start due to the IR drop. This problem won't
exist with a diode string when used as a voltage dropping method.
73
Bob, K4TAX
----- Original Message -----
From: "K8JHR" <jrichards@k8jhr.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Friday, March 07, 2014 7:36 AM
Subject: Re: [TenTec] Noise from Fans
Thanks for the uptake, Rick.
Ah, yes... Heat. I picked a really big resistor so I assume it is OK. I
will have to check it. The guy who maintains our 17-site repeater system
specified the value for me. I buy him lots of beer ...
----------------- JHR ---------------------------
On 3/7/2014 4:07 AM, Rick - DJ0IP / NJ0IP wrote:
The resistor probably gets pretty hot.
The diode string does not.
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