If you run across a copy of Walter Jung's IC Timer Cookbook, there is as
you'd expect a large selection of circuits for various timer chips.  The
most common basic chip is the 555, here's a link to get you going:
http://www.555-timer-circuits.com/

Yrs,
d

On Wed, Aug 2, 2017 at 4:09 PM, Neil N <musomuso@gmail.com> wrote:

> Thanks for that David. I've been so involved in other wiring projects,
> haven't read this thread yet.
>
> Thats a sizeable cap! Image showing measurements:
>
> http://tinyurl.com/ybxpvnx5
>
> I did see your comment on semiconductors being used for this type of
> circuit.
>
> On 8/2/17, David Beierl <dbeierl@attglobal.net> wrote:
>
> > Osram DE3423 LED festoon lamp is one watt.  If you want ten seconds of
> > fading light at average half brightness that would require something like
> > five watt seconds of storage in your capacitor.  Say six or seven because
> > of the threshold voltage of the LED.  WS = C x V^2 / 2, so C = WS / (V^2
> /
> > 2).  So C = 7 ws / (12V^2 / 2) = 7 / 72 = ~0.1 farad or 100,000 uF.
> >
> > Here's one that would serve.  It's nominal 40 mm diameter and 80 mm
> length,
> > and it costs ten bucks US in onesies.
> > https://www.digikey.com/product-detail/en/united-
> chemi-con/ESMH160VSN104MA80T/565-2624-ND/757837
> >
> > Yrs,
> > d
> >
> >
> >
> > On Wed, Aug 2, 2017 at 1:32 PM, Neil N <musomuso@gmail.com> wrote:
> >
> >> Thats great! So about 5 seconds eh? I'd think that for a festoon the
> >> cap(s) would have to be much bigger. But maybe 3 of those small LED's
> >> would be plenty?
> >>
> >
>
>
> --
> Neil n
>
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>
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>
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>
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>