DIY 12V Delay - Possible? - Page 2 - diyAudio
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Old 16th June 2006, 01:18 PM   #11
quasi is offline quasi  Australia
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Location: Adelaide, Australia
The circuit posted by Gmphadte whilst perfect for holding up interior lights is not suitable for providing a delay for power windows. I can think of 2 main reasons for this.

1. The currents drawn by the motors on startup will far exceed the capability of the 2N3055 and probably destroy it. During the fade-out period of this circuit, the current drawn by the motor will actually increase (especially when it finally stalls).

2. The back EMF will probably destroy the transistor, and because of the polarity reversal on these motors (up/down) it is not easy to fix.

A relay is the safest way to solve this and the circuit attached is what I had in mind. Simple I know, but if only rough timing is required then it's adequate and cheap.

Choose R1 & C1 to achieve the delay required.

Cheers
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File Type: gif power delay.gif (3.8 KB, 51 views)
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