Neil,

Where is my brain? I just remembered I bought a delay timer really unit from banggood. It's this one

Geekcreit® DC 12V LED Display Digital Delay Timer Control Switch Module PLC
https://banggood.app.link/YobsCIrqiF

I haven't tried it, and I forget why I bought it :-)

But i think it might be a solution for you. It's not very big.  Up to 999 second delay via a relay. Maybe I'll set it up on the breadboard to give you an idea of how it works. And give me an idea of how it works.

Alistair

> On Aug 2, 2017, at 1:09 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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