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Old 19th December 2012, 10:37 PM   #11
Alkis is offline Alkis  Greece
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Then use an output relay with a small disc-shaped capacitor connected between the contacts, in conjunction with a delay relay. I presume you don't have an output transformer.
And give your girlfriend the proper directions
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Old 20th December 2012, 12:30 PM   #12
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... but the cap will delay turnoff! How do you solve this?

Dirk
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Old 20th December 2012, 01:06 PM   #13
Alkis is offline Alkis  Greece
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????? ????? ?????.
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Old 21st December 2012, 10:01 PM   #14
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Cap delays switchon, but also switchoff - correct?
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Old 22nd December 2012, 02:55 AM   #15
TheGimp is offline TheGimp  United States
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A diode across the resistor will discharge the cap rapidly at power off. Simple CPU POR trick.
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Old 22nd December 2012, 01:32 PM   #16
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Hi,

I think, I have a fundamentalmisunderstanding: A (quite huge) cap takes time to build up the voltage. So relay is delayed. But how can i use the diode? Forward bias would prevent the cap getting charged, reverse bias will do nothing. Can you post a schematic to clarify?

Dirk
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Old 22nd December 2012, 03:25 PM   #17
TheGimp is offline TheGimp  United States
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Reverse bias will do nothing during the charge phase (power on). However, at power off the diode will become forward biased and rapidly discharge the cap.
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Old 22nd December 2012, 04:42 PM   #18
Jaap is offline Jaap  Netherlands
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Zeitsteuerungs-Bausätze - im Conrad Online Shop günstig kaufen
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Old 22nd December 2012, 10:20 PM   #19
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Hi TheGimp,

please post a schematic, I think, I have a misunderstanding:

Reverse bias will do nothing during the charge phase (power on). OK

at power off the diode will become forward biased NO!!! Voltage stays reverse based, but will decrease...

Where is my misunderstanding???
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Old 22nd December 2012, 10:38 PM   #20
TheGimp is offline TheGimp  United States
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Like this:
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