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Subject: Re: How to get CMOS counter to drive a relay?
Date: Tue, 22 Oct 2002 03:46:51 -0700
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References: <0001HW.B9CEF278023A90B81662EAD0@news.covad.net> <3DA9D6CC.firstname.lastname@example.org> <3DA9D9E1.email@example.com> <3DA9EE2A.B7CFD919@juno.com> <3DAAF96D.firstname.lastname@example.org> <3DAB71EC.DB68183C@juno.com> <3DAC2309.email@example.com> <firstname.lastname@example.org> <3DAFFA70.email@example.com> <firstname.lastname@example.org> <3DB1869F.649A02A4@bellatlantic.net> <email@example.com> <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org>
An interesting experiment might be to put a current probe on
relay coil lead. There are only two places for the energy to
In the coil losses and back into the driver.
With a 20mA relay, I'd expect most of that 20mA going back into
Even with the clamp diode, I'd worry a about the flyback
almost a volt above the CMOS supply. Not a problem with an
Just because it works once or twice or 100 times doesn't make
I've spent a lot of time fixing up designs that had worked fine
for a year or more in production then suddenly went to hell
when a vendor
decided to use different floor-sweepings for a part.
Bunch of stuff For Sale and Wanted at the link below.
Tek 2465, TFT projector, Transoceanic, ham radio, 30pS pulser
Tektronix Concept Books...
Tony Williams wrote:
> In article <email@example.com>,
> Frank Bemelman wrote:
> > Okay. The flyback causes the output to rise 2 volts above
> > the supply, for a few ms, decaying quickly. (without the
> > diode). I had it run for half an hour, sweeping the
> > frequency from 1Hz to 100Hz. Tckckrrrreeeeetttssss....
> > I also have to report that the 4060 finally died at 25V.
> > It didn't suffer very long ;)
> Try it the other way Frank..... with the free end
> of the relay coil to 0v. See if there is any
> difference when an output pin is thrown below 0V.
> (ie, below the substrate.)
> Tony Williams.
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