Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Zen Cycle <funkmaster@hotmail.com>
Newsgroups: rec.bicycles.tech
Subject: Re: Ove Interest?
Date: Mon, 3 Mar 2025 10:38:34 -0500
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On 2/28/2025 7:42 PM, Jeff Liebermann wrote:
> On Fri, 28 Feb 2025 13:24:33 -0500, Zen Cycle <funkmaster@hotmail.com>
> wrote:
> 
>> On 2/28/2025 12:24 PM, Jeff Liebermann wrote:
>>> On Fri, 28 Feb 2025 15:42:05 GMT, cyclintom <cyclintom@yahoo.com>
>>> wrote:
>>>
>>>> But now the man who admitted he doesn't know shit about digital design is suddenly an expert at it.
>>>
>>> TDR (time domain reflectometry) is mostly analog, not digital.  You
>>> might argue that it can be used to impedance match transmission lines
>>> and circuit traces on digital PCB's (printed circuit boards) or that
>>> the required fast rise time pulse generator can be done digitally.
>>> However, as long as the measurements are most commonly displayed on an
>>> analog oscilloscope, methinks that TDR should be considered (mostly)
>>> an analog technology.
>>>
>>> Also, there's nothing to "design" with TDR.  It's a measurement
>>> technique performed using off the shelf test equipment.  Your claim
>>> that to understand TDR somehow requires a digital designer suggests
>>> that you haven't done any TDR measurements (with or without PWM) and
>>> know little about what is involved.  This might help:
>>>
>>> <https://www.tek.com/en/documents/primer/tdr-test>
>>> "Time Domain Reflectometry (TDR) has traditionally been used for
>>> locating faults in cables."
>>>
>>> I've mentioned this previously, but it's worth repeating.  The way I
>>> recognize expertise in any technical discipline is if the person
>>> claiming expertise knows the vocabulary, buzzwords, acronyms, inside
>>> jokes, and literature used by knowledgeable practitioners.  You have
>>> repeatedly incorrectly spelled and misused technical terms that anyone
>>> experienced in the field would be expected to know.
>>
>> +1
>> Remember "time delay reflection"? lol
>> https://groups.google.com/g/rec.bicycles.tech/c/f_tByXh5jXo/m/9Y4EzuUJCAAJ
> 
> Yep.  One of many such mistakes caused by Tom not understanding the
> terminology and the technology.  From the above URL:
> 
> "...there is absolutely no way that I am going to explain to people
> how to use pulse width modulation to achieve time delay reflection."
> 
> Actually, that's true.  There is no way he can explain something that
> is totally wrong and/or doesn't exist.
> 
> More entertainment.  Further down the same thread are my replies to
> Tom's comments about having a very short battery life on his Garmin
> HRM, where the battery allegedly died in "a couple of weeks":
> <https://groups.google.com/g/rec.bicycles.tech/c/f_tByXh5jXo/m/fLccSwscCAAJ>
> 

Here's an interesting data point. It turns out that 1st generation HRM 
Pro had an issue where they would allow water ingress which would kill 
the battery after a few days. Keep in mind this product was marketed for 
triathlon use.

I found out about this the hard way - Last spring we took a vacation to 
Aruba. I rented a Mountain Bike and one of the days took a long ride (in 
the Aruban 85-90 degrees 85% RH with 25 mph wind)

https://www.strava.com/activities/11425440602

When I got back I was exhausted, dropped the bike at the side of the 
pool and fell in. The next day, the HRM was dead (this was a two year 
old unit that I bought new and had never had any problems with).

I replaced the battery, went and went for a run. A few days after we got 
back, it was dead again.  I went through two more iterations, did some 
research on-line and found that the seals on that version deteriorate 
over time and allow ingress when immersed. Also in the forums there are 
discussions that the older tiny retention screws on the battery covers 
don't hold the plastic as well after a couple of battery changes which 
affects the ability of the cover to seal.

The above two issue generally aren't a problem if you never immerse the 
HRM.

I replaced the HRM with the 2nd gen version last summer (new directly 
from Garmin), the new version has a tool-less battery cover. I replaced 
the battery a few weeks ago after a full spring/summer/fall of use in 
preparation for the trip to St. Croix we took last month, still seems to 
be working.

This Brings us to Toms issue: Tom bought it off ebay, allegedly new (but 
not from a retailer). He claimed to have two, neither of which would 
last more than a few weeks. I submit that he got yet another "deal" off 
ebay in which someone had one of these failures and decided to sell to 
some unsuspecting rube.

The short answer is: no, it's not normal for a Garmin HRM to only last a 
few weeks, even under daily use. So we're back to either tom telling us 
portions of the tale that aren't true (the HRMs were new, he used 
name-brand batteries), or the fact that he was sold defective parts.


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