Hi Didier:
I know CMAX had a real problem with their LF time receiver boards. The
high value caps used to resonate the loop-stick antenna permanently
changed value so much when heated to soldering temperature they no
longer worked. Now they use radial lead caps shrink wrapped to the
loop-sticks instead of having the cap on the receiver PCB.
Have Fun,
Brooke Clarke
http://www.PRC68.com
shali...@gmail.com wrote:
Also they are almost impossible to solder by hand without setting high internal
stress which sometimes results in cracks, not necessarily immediately. Even on
professional wave solder equipment, high delayed failure rates are not
uncommon, which sometimes results in many units having to be recalled. Don't
ask me how I know, I was lucky this was not my design, but it could have been.
Yet, I still use them, under the assurance that our manufacturing folks have
resolved the problem, which for now seems true.
Didier
Sent from my Verizon Wireless BlackBerry
-----Original Message-----
From: Chuck Harris<cfhar...@erols.com>
Sender: time-nuts-boun...@febo.com
Date: Sun, 16 Jan 2011 17:43:18
To: Discussion of precise time and frequency measurement<time-nuts@febo.com>
Reply-To: Discussion of precise time and frequency measurement
<time-nuts@febo.com>
Subject: Re: [time-nuts] GC-1000 Clock Cap Choice?
I have found that such high dielectric constant capacitors have other
problems in some circuits. While the capacitance value is dropping,
as much as 50% when you apply voltage, their physical volume is
changing. They behave as piezoelectric transducers.
I have used them inappropriately, and found them singing loudly. If
that were to happen in a switching regulator, I would think the ultrasonic
vibrations could do damage to the capacitor, the PCB, or the solder joints.
-Chuck Harris
Poul-Henning Kamp wrote:
In message<4d336a19.40...@freenet.de>, "Dr. Frank Stellmach" writes:
High cap value Ceramics are available since years, [...]
Can you clarify one thing for me: When I studied datasheets for these
it looked like they drop 50% of their capacitance at a DC voltage
of 10-20V.
Doesn't that make them a so-so bargain for power supply bulk capacitance ?
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