Good tidbit on the cmax On Thu, Jan 20, 2011 at 10:29 AM, Brooke Clarke <[email protected]> wrote:
> 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 > > > [email protected] 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<[email protected]> >> Sender: [email protected] >> Date: Sun, 16 Jan 2011 17:43:18 >> To: Discussion of precise time and frequency measurement< >> [email protected]> >> Reply-To: Discussion of precise time and frequency measurement >> <[email protected]> >> 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<[email protected]>, "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 >>> ? >>> >>> >>> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> >> >> > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
